Rollback setup-dotnet action (#940)

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applicable)

When we upgraded the setup-dotnet action from v1 to v3 yesterday it
caused our builds to get significantly longer (3.5min -> 8.5 min for one
job).

I narrowed it down to something specifically in v3.0.0 of that action. I
will open an issue for the team that owns that action to hopefully help
us shed some more light on what's going on, in the meantime this PR
rolls us back to v2.

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.github/workflows/CI.yml

@@ -31,7 +31,7 @@ jobs:
         config-file: ./.github/codeql/codeql-config.yml
 
     - name: Setup .NET
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v2
       with:
         dotnet-version: 6.0.x
 
@@ -101,7 +101,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup .NET
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v2
       with:
         dotnet-version: 6.0.x
 
@@ -158,7 +158,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup .NET
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v2
       with:
         dotnet-version: 6.0.x
 
@@ -305,7 +305,7 @@ jobs:
         }
 
     - name: Setup .NET
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v2
       with:
         dotnet-version: 6.0.x
 

.github/workflows/integration-tests.yml

@@ -18,7 +18,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Setup .NET
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v2
       with:
         dotnet-version: 6.0.x
 
@@ -83,7 +83,7 @@ jobs:
         echo "PR_SHA=$(echo $prsha)" >> $GITHUB_ENV
 
     - name: Setup .NET
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v2
       with:
         dotnet-version: 6.0.x