Update actions/cache to v3 in CI workflow

- Replaced actions/cache@v2 with v3 to avoid deprecation warnings.

.github/workflows/scala.yml

@@ -29,15 +29,15 @@ jobs:
         run: source .github/workflows/tools.sh && install_packages
 
       - name: Cache pip
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: ~/.cache/pip
-          key: ${{ runner.os }}-pip-v2
+          key: ${{ runner.os }}-pip-v3
           restore-keys: |
             ${{ runner.os }}-pip-
 
       - name: Cache SBT
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: |
             ~/.ivy2/cache
@@ -46,7 +46,7 @@ jobs:
 
       - name: Cache tools
         id: tools
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: |
             ~/tools