Update actions/cache action to v6

Author: renovate[bot]

.github/workflows/versioning-merge.yml

@@ -31,7 +31,7 @@ jobs:
 
     - name: Cache Helm binary
       id: cache-helm
-      uses: actions/cache@v5
+      uses: actions/cache@v6
       with:
         path: /usr/local/bin/helm
         key: helm-v3.19.0-linux-amd64

.github/workflows/versioning.yml

@@ -23,7 +23,7 @@ jobs:
 
         - name: Cache Helm binary
           id: cache-helm
-          uses: actions/cache@v5
+          uses: actions/cache@v6
           with:
             path: /usr/local/bin/helm
             key: helm-v3.19.0-linux-amd64