Try skipping that step.

Author: JimBobSquarePants

.github/workflows/build-and-test.yml

@@ -45,16 +45,6 @@ jobs:
                   git fetch --prune --unshallow
                   git submodule -q update --init --recursive
 
-            - name: Setup DotNet SDK 3.1
-              uses: actions/setup-dotnet@v1
-              with:
-                  dotnet-version: "3.1.x"
-
-            - name: Setup DotNet SDK 2.1
-              uses: actions/setup-dotnet@v1
-              with:
-                  dotnet-version: "2.1.x"
-
             - name: Install Azurite Linux
               if: matrix.options.os == 'ubuntu-latest'
               shell: bash
@@ -110,16 +100,6 @@ jobs:
                   git fetch --prune --unshallow
                   git submodule -q update --init --recursive
 
-            - name: Setup DotNet SDK 3.1
-              uses: actions/setup-dotnet@v1
-              with:
-                  dotnet-version: "3.1.x"
-
-            - name: Setup DotNet SDK 2.1
-              uses: actions/setup-dotnet@v1
-              with:
-                  dotnet-version: "2.1.x"
-
             - name: Pack
               shell: pwsh
               run: ./ci-pack.ps1