[CI] nuke opam cache for mac

.github/workflows/main.yml

@@ -472,7 +472,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: ~/.opam/
-          key: ${{ matrix.os }}-${{ hashFiles('./haxe.opam', './libs/') }}
+          key: ${{ matrix.os }}-${{ hashFiles('./haxe.opam', './libs/') }}-1
 
       - name: Install Neko from S3
         run: |

extra/github-actions/workflows/main.yml

@@ -326,7 +326,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: ~/.opam/
-          key: ${{ matrix.os }}-${{ hashFiles('./haxe.opam', './libs/') }}
+          key: ${{ matrix.os }}-${{ hashFiles('./haxe.opam', './libs/') }}-1
 
       @import install-neko-unix.yml
       @import build-mac.yml