Bump actions/cache from 2.1.5 to 2.1.6

Bumps [actions/cache](https://github.com/actions/cache) from 2.1.5 to 2.1.6.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v2.1.5...v2.1.6)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -44,7 +44,7 @@ jobs:
     -
       name: Cache cake frosting
       id: cache-cake
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: run
         key: run-${{ runner.os }}-${{ hashFiles('./build/**') }}
@@ -72,14 +72,14 @@ jobs:
     -
       name: Use cached cake frosting
       id: cache-cake
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: run
         key: run-${{ runner.os }}-${{ hashFiles('./build/**') }}
     -
       name: Use cached tools
       id: cache-tools
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: tools
         key: tools-${{ runner.os }}-${{ hashFiles('./build/**') }}
@@ -123,14 +123,14 @@ jobs:
     -
       name: Use cached cake frosting
       id: cache-cake
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: run
         key: run-${{ runner.os }}-${{ hashFiles('./build/**') }}
     -
       name: Use cached tools
       id: cache-tools
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: tools
         key: tools-${{ runner.os }}-${{ hashFiles('./build/**') }}
@@ -158,14 +158,14 @@ jobs:
     -
       name: Use cached cake frosting
       id: cache-cake
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: run
         key: run-${{ runner.os }}-${{ hashFiles('./build/**') }}
     -
       name: Use cached tools
       id: cache-tools
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: tools
         key: tools-${{ runner.os }}-${{ hashFiles('./build/**') }}
@@ -200,14 +200,14 @@ jobs:
     -
       name: Use cached cake frosting
       id: cache-cake
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: run
         key: run-${{ runner.os }}-${{ hashFiles('./build/**') }}
     -
       name: Use cached tools
       id: cache-tools
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: tools
         key: tools-${{ runner.os }}-${{ hashFiles('./build/**') }}
@@ -248,14 +248,14 @@ jobs:
     -
       name: Use cached cake frosting
       id: cache-cake
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: run
         key: run-${{ runner.os }}-${{ hashFiles('./build/**') }}
     -
       name: Use cached tools
       id: cache-tools
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: tools
         key: tools-${{ runner.os }}-${{ hashFiles('./build/**') }}
@@ -311,14 +311,14 @@ jobs:
     -
       name: Use cached cake frosting
       id: cache-cake
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: run
         key: run-${{ runner.os }}-${{ hashFiles('./build/**') }}
     -
       name: Use cached tools
       id: cache-tools
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: tools
         key: tools-${{ runner.os }}-${{ hashFiles('./build/**') }}
@@ -349,14 +349,14 @@ jobs:
     -
       name: Use cached cake frosting
       id: cache-cake
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: run
         key: run-${{ runner.os }}-${{ hashFiles('./build/**') }}
     -
       name: Use cached tools
       id: cache-tools
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: tools
         key: tools-${{ runner.os }}-${{ hashFiles('./build/**') }}

.github/workflows/docs.yml

@@ -21,7 +21,7 @@ jobs:
     -
       name: Cache cake frosting
       id: cache-cake
-      uses: actions/[email protected].5
+      uses: actions/[email protected].6
       with:
         path: run
         key: run-docs-${{ runner.os }}-${{ hashFiles('./build/**') }}