Fix TiUP cache to save updates when versions change

- Add dynamic cache key that includes TiDB versions hash
- Cache key now includes workflow hash, go.mod hash, and TiDB versions hash
- This ensures cache updates are saved when TiDB versions change
- Both prepare-dependencies and tests jobs use same cache key for sharing
- Cache automatically cleans up after 7 days (no explicit cleanup needed)

Previously, static cache key caused 'not saving cache' on cache hits,
preventing updates from being saved. Now cache properly invalidates
and saves when versions change.

Author: zph

.github/workflows/main.yml

@@ -75,13 +75,21 @@ jobs:
       - name: Vendor Go dependencies
         run: go mod vendor
 
+      - name: Generate TiDB versions hash
+        id: tidb-versions-hash
+        run: |
+          echo "hash=$(echo '${{ env.TIDB_VERSIONS }}' | sha256sum | cut -d' ' -f1 | cut -c1-8)" >> $GITHUB_OUTPUT
+      
       - name: Cache TiUP components
+        id: cache-tiup
         uses: actions/cache@v4
         with:
           path: |
             ~/.tiup
-          key: ${{ runner.os }}-tiup-components
+          # Include workflow hash and TiDB versions hash in cache key so cache updates when versions change
+          key: ${{ runner.os }}-tiup-${{ hashFiles('.github/workflows/main.yml') }}-${{ hashFiles('**/go.mod') }}-${{ steps.tidb-versions-hash.outputs.hash }}
           restore-keys: |
+            ${{ runner.os }}-tiup-${{ hashFiles('.github/workflows/main.yml') }}-${{ hashFiles('**/go.mod') }}-
             ${{ runner.os }}-tiup-
       
       - name: Install TiUP
@@ -188,14 +196,23 @@ jobs:
           sudo apt-get update -qq
           sudo apt-get install -y --no-install-recommends mysql-client
       
+      - name: Generate TiDB versions hash
+        id: tidb-versions-hash-test
+        if: contains(matrix.target, 'tidb')
+        run: |
+          echo "hash=$(echo '${{ env.TIDB_VERSIONS }}' | sha256sum | cut -d' ' -f1 | cut -c1-8)" >> $GITHUB_OUTPUT
+      
       - name: Cache TiUP components
+        id: cache-tiup-test
         if: contains(matrix.target, 'tidb')
         uses: actions/cache@v4
         with:
           path: |
             ~/.tiup
-          key: ${{ runner.os }}-tiup-components
+          # Use same cache key as prepare-dependencies job to share cache
+          key: ${{ runner.os }}-tiup-${{ hashFiles('.github/workflows/main.yml') }}-${{ hashFiles('**/go.mod') }}-${{ steps.tidb-versions-hash-test.outputs.hash }}
           restore-keys: |
+            ${{ runner.os }}-tiup-${{ hashFiles('.github/workflows/main.yml') }}-${{ hashFiles('**/go.mod') }}-
             ${{ runner.os }}-tiup-
       
       - name: Install TiUP (if not cached)