CI: bump cache key

Author: bukka

.github/workflows/main.yml

@@ -43,7 +43,7 @@ jobs:
           cache-name: cache-ImageMagick
         with:
           path: ~/im/imagemagick-${{ matrix.imagemagick }}
-          key: ${{ runner.os }}-ImageMagick-${{ matrix.imagemagick }}
+          key: ${{ runner.os }}-ubuntu22-ImageMagick-${{ matrix.imagemagick }}
 
       - name: Sanity check package.xml and install ImageMagick
         run: |
@@ -159,7 +159,7 @@ jobs:
           cache-name: cache-ImageMagick
         with:
           path: ~/im/imagemagick-${{ matrix.imagemagick }}
-          key: ${{ runner.os }}-ImageMagick-${{ matrix.imagemagick }}
+          key: ${{ runner.os }}-ubuntu22-ImageMagick-${{ matrix.imagemagick }}
 
       - name: Sanity check package.xml and install ImageMagick
         run: |