CI: add a clean cache workflow_dispatch option

Author: messense

.github/workflows/Build.yml

@@ -4,6 +4,11 @@ on:
       - master
   pull_request:
   workflow_dispatch:
+    inputs:
+      clean_cache:
+        description: Clean Docker cache before build, yes/no
+        default: 'no'
+        required: false
   schedule:
     - cron: '0 0 1 */2 *'
 
@@ -125,7 +130,7 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-${{ matrix.os.arch }}-${{ matrix.env.TARGET }}-buildx-
       - name: Clean Docker cache
-        if: "contains(github.event.head_commit.message, '[clean cache]')"
+        if: ${{ contains(github.event.head_commit.message, '[clean cache]') || github.event.inputs.clean_cache == 'yes' }}
         continue-on-error: true
         run: |
           rm -rf /tmp/.buildx-cache