build: use new setup-python caching

Author: nedbat

.github/workflows/coverage.yml

@@ -60,6 +60,8 @@ jobs:
         uses: "actions/setup-python@v2"
         with:
           python-version: "${{ matrix.python-version }}"
+          cache: pip
+          cache-dependency-path: 'requirements/*.pip'
 
       - name: "Install dependencies"
         run: |
@@ -97,6 +99,8 @@ jobs:
         uses: "actions/setup-python@v2"
         with:
           python-version: "3.8"
+          cache: pip
+          cache-dependency-path: 'requirements/*.pip'
 
       - name: "Install dependencies"
         run: |

.github/workflows/kit.yml

@@ -111,6 +111,8 @@ jobs:
         uses: actions/setup-python@v2
         with:
           python-version: "3.8"
+          cache: pip
+          cache-dependency-path: 'requirements/*.pip'
 
       - name: "Install tools"
         run: |
@@ -153,6 +155,8 @@ jobs:
         uses: actions/setup-python@v2
         with:
           python-version: "3.8"
+          cache: pip
+          cache-dependency-path: 'requirements/*.pip'
 
       - name: "Install tools"
         run: |
@@ -183,6 +187,8 @@ jobs:
         uses: actions/setup-python@v2
         with:
           python-version: "pypy3"
+          cache: pip
+          cache-dependency-path: 'requirements/*.pip'
 
       - name: "Install requirements"
         run: |
@@ -226,6 +232,8 @@ jobs:
         uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.py }}
+          cache: pip
+          cache-dependency-path: 'requirements/*.pip'
 
       - name: "Install wheel tools"
         run: |

.github/workflows/quality.yml

@@ -34,6 +34,8 @@ jobs:
         uses: "actions/setup-python@v2"
         with:
           python-version: "3.8"
+          cache: pip
+          cache-dependency-path: 'requirements/*.pip'
 
       - name: "Install dependencies"
         run: |
@@ -58,6 +60,8 @@ jobs:
         uses: "actions/setup-python@v2"
         with:
           python-version: "3.8"
+          cache: pip
+          cache-dependency-path: 'requirements/*.pip'
 
       - name: "Install dependencies"
         run: |

.github/workflows/testsuite.yml

@@ -54,6 +54,8 @@ jobs:
         uses: "actions/setup-python@v2"
         with:
           python-version: "${{ matrix.python-version }}"
+          cache: pip
+          cache-dependency-path: 'requirements/*.pip'
 
       - name: "Install dependencies"
         run: |