fix github workflows.

.github/workflows/build.yml

@@ -2,21 +2,21 @@ name: Build
 
 on:
   push:
-    branches: [ master ]
+    branches: [ releases/8.x ]
   pull_request:
-    branches: [ master ]
+    branches: [ releases/8.x ]
 
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Setup .NET
-      uses: actions/setup-dotnet@v1
+      uses: actions/setup-dotnet@v4
       with:
-        dotnet-version: 5.0.x
+        dotnet-version: 6.0.x
     - name: Restore dependencies
       run: dotnet restore ./src/AspNetCore.Identity.Mongo/
     - name: Build