Use windows bash compatible envs

Signed-off-by: James Sturtevant <jsturtevant@gmail.com>

Author: jsturtevant

.github/workflows/build.yml

@@ -48,10 +48,10 @@ jobs:
     - name: Test Template
       shell: bash
       run: |
-        artifact_dir=${{ github.workspace }}/artifacts
+        artifact_dir=$GITHUB_WORKSPACE/artifacts
         dotnet new install ./artifacts/BytecodeAlliance.Componentize.DotNet.Templates.*.nupkg
-        mkdir ${{ runner.temp }}/projects
-        pushd ${{ runner.temp }}/projects
+        mkdir $RUNNER_TEMP/projects
+        pushd $RUNNER_TEMP/projects
         dotnet new componentize.wasi.cli -o test
         cd test
         dotnet nuget add source $artifact_dir