qa: nuke caches on CI descriptor change

Adds a nonce field to manually nuke the cache

Changing the CI workflow descriptor can invalidate dependencies
and ccache caches by introducing different compilers or base OS,
but as GH Actions does not let us update an existing cache, this
would cause every subsequent CI run to rebuild everything until
a nuke is triggered.

.github/workflows/ci.yml

@@ -21,6 +21,7 @@ jobs:
       CCACHE_TEMPDIR: /tmp/.ccache-temp
       CCACHE_COMPRESS: "1"
       PYTHON_DEBUG: "1"
+      CACHE_NONCE: "1"
       WINEDEBUG: fixme-all
       SDK_URL: https://bitcoincore.org/depends-sources/sdks
 
@@ -182,7 +183,7 @@ jobs:
           cache-name: depends
         with:
           path: ./depends/built
-          key: ${{ matrix.name }}-${{ env.cache-name }}-${{ hashFiles('depends/packages/*') }}
+          key: ${{ matrix.name }}-${{ env.cache-name }}-${{ hashFiles('depends/packages/*', '.github/workflows/ci.yml') }}
 
       - name: Build depends
         run: |
@@ -194,7 +195,7 @@ jobs:
           cache-name: ccache
         with:
           path: ~/.ccache
-          key: ${{ matrix.name }}-${{ env.cache-name }}-${{ hashFiles('**/configure.ac') }}
+          key: ${{ matrix.name }}-${{ env.cache-name }}-${{ hashFiles('**/configure.ac', '.github/workflows/ci.yml') }}
 
       - name: Build Dogecoin
         run: |