Use Java version in community-build

Author: nicolasstucki

.github/workflows/ci.yaml

@@ -263,6 +263,9 @@ jobs:
          )"
 
     steps:
+      - name: Set JDK 15 as default
+        run: echo "/usr/lib/jvm/java-15-openjdk-amd64/bin" >> $GITHUB_PATH
+
       - name: Reset existing repo
         run: git -c "http.https://github.com/.extraheader=" fetch --recurse-submodules=no "https://github.com/lampepfl/dotty" && git reset --hard FETCH_HEAD || true
 
@@ -310,6 +313,9 @@ jobs:
          )"
 
     steps:
+      - name: Set JDK 15 as default
+        run: echo "/usr/lib/jvm/java-15-openjdk-amd64/bin" >> $GITHUB_PATH
+
       - name: Reset existing repo
         run: git -c "http.https://github.com/.extraheader=" fetch --recurse-submodules=no "https://github.com/lampepfl/dotty" && git reset --hard FETCH_HEAD || true
 
@@ -357,6 +363,9 @@ jobs:
          )"
 
     steps:
+      - name: Set JDK 17 as default
+        run: echo "/usr/lib/jvm/java-17-openjdk-amd64/bin" >> $GITHUB_PATH
+
       - name: Reset existing repo
         run: git -c "http.https://github.com/.extraheader=" fetch --recurse-submodules=no "https://github.com/lampepfl/dotty" && git reset --hard FETCH_HEAD || true