Revert setup-dotnet with global-json-file

Otherwise we would either need to update global.json regularly or we would not use a recent version of .NET unless e.g. actions/setup-dotnet#481 is merged.

Author: georg-jung

.github/workflows/create-release.yml

@@ -15,7 +15,7 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v4
       with:
-        global-json-file: global.json
+        dotnet-version: '8.0.x'
 
     - name: Replace Version in csproj files
       run: |

.github/workflows/publish-docfx-to-pages.yml

@@ -26,7 +26,7 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v4
       with:
-        global-json-file: global.json
+        dotnet-version: '8.0.x'
 
     - name: Install docfx
       run: dotnet tool install -g docfx

.github/workflows/test-pull-request.yml

@@ -13,7 +13,7 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v4
       with:
-        global-json-file: global.json
+        dotnet-version: 8.0.x
     - name: Restore dependencies
       run: dotnet restore
     - name: Build

.github/workflows/test-push.yml

@@ -13,7 +13,7 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v4
       with:
-        global-json-file: global.json
+        dotnet-version: 8.0.x
     - name: Restore dependencies
       run: dotnet restore
     - name: Build