chore: increment GOCACHE key (#8849)

.github/actions/setup-go/action.yaml

@@ -39,24 +39,25 @@ runs:
         path: |
           ${{ env.GOMODCACHE }}
         key: gomodcache-${{ runner.os }}-${{ hashFiles('**/go.sum') }}-${{ github.job }}
-        restore-keys: |
-          gomodcache-${{ runner.os }}-${{ hashFiles('**/go.sum') }}-
-          gomodcache-${{ runner.os }}-
+        # restore-keys aren't used because it causes the cache to grow
+        # infinitely. go.sum changes very infrequently, so rebuilding from
+        # scratch every now and then isn't terrible.
 
     - name: Cache $GOCACHE
       uses: buildjet/cache@v3
       with:
         path: |
           ${{ env.GOCACHE }}
-        # Job name must be included in the key for effective
-        # test cache reuse.
+        # Job name must be included in the key for effective test cache reuse.
         # The key format is intentionally different than GOMODCACHE, because any
-        # time a Go file changes we invalidate this cache, whereas GOMODCACHE
-        # is only invalidated when go.sum changes.
-        key: gocache-${{ runner.os }}-${{ github.job }}-${{ hashFiles('**/*.go', 'go.**') }}
+        # time a Go file changes we invalidate this cache, whereas GOMODCACHE is
+        # only invalidated when go.sum changes.
+        # The number in the key is incremented when the cache gets too large,
+        # since this technically grows without bound.
+        key: gocache2-${{ runner.os }}-${{ github.job }}-${{ hashFiles('**/*.go', 'go.**') }}
         restore-keys: |
-          gocache-${{ runner.os }}-${{ github.job }}-
-          gocache-${{ runner.os }}-
+          gocache2-${{ runner.os }}-${{ github.job }}-
+          gocache2-${{ runner.os }}-
 
     - name: Install gotestsum
       shell: bash