Revert "ci: always run setup-dotnet, run it earlier, and let it handle caching"

This reverts commit fdea79d.

Author: lilith

.github/workflows/dotnet-core.yml

@@ -46,22 +46,12 @@ jobs:
     runs-on: ${{matrix.os}}
     steps:     
     - uses: actions/checkout@v4
-      
-    - name: Check .NET versions available
-      shell: bash
-      run: |
-        echo "DOTNET_VERSION_LIST<<EOF" >> $GITHUB_ENV
-        dotnet --list-sdks >> $GITHUB_ENV
-        echo "EOF" >> $GITHUB_ENV
-        dotnet --list-sdks
-
-    - name: Setup .NET 6,8
-      uses: actions/setup-dotnet@v4
+    - uses: actions/cache@v4
+      id: cache
       with:
-        cache: ${{ matrix.cache_dependencies }}
-        dotnet-version: |
-          6.x
-          8.x
+        path: ~/.nuget/packages
+        key: ${{ runner.os }}-nuget-breaker3-${{ hashFiles('**/packages.lock.json') }}
+      if: matrix.cache_dependencies
 
     - uses: nowsprinting/check-version-format-action@v4
       id: version
@@ -94,7 +84,20 @@ jobs:
         echo Set HOST_ZIP_FILE to ${{ env.HOST_ZIP_FILE }}
       shell: bash
 
-
+    - name: Check .NET versions available to see if we can skip install
+      shell: bash
+      run: |
+        echo "DOTNET_VERSION_LIST<<EOF" >> $GITHUB_ENV
+        dotnet --list-sdks >> $GITHUB_ENV
+        echo "EOF" >> $GITHUB_ENV
+        dotnet --list-sdks
+      
+    - name: Setup .NET 6,8
+      uses: actions/setup-dotnet@v4
+      if:  contains(env.DOTNET_VERSION_LIST, '8.0.') == 'false' || contains(env.DOTNET_VERSION_LIST, '6.0.') == 'false'
+      with:
+        dotnet-version: "6\n8\n"
+        
     - name: Clear & clean on release or cache miss
       run: |
         dotnet clean --configuration Release