Upgrade to actions/cache v4

Author: lesserwhirls

.github/workflows/threddsIso-tests.yml

@@ -18,7 +18,7 @@ jobs:
           java-version: ${{ matrix.java }}
           distribution: ${{ matrix.distribution }}
       - name: Cache local Maven repository
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: ~/.m2/repository
           key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}