upload coverage results to codecov on Ubuntu image

Author: tonerdo

Diff for: appveyor.yml

@@ -6,7 +6,13 @@ configuration:
   - Debug
   - Release
 build_script:
-  - ps: echo "Building for $env:CONFIGURATION"
+  - ps: echo "Building for $env:CONFIGURATION on $env:APPVEYOR_BUILD_WORKER_IMAGE"
   - ps: dotnet msbuild build.proj /p:Configuration=$env:CONFIGURATION
 test_script:
-  - ps: if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }
+  - ps: if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }
+  - ps: |
+      if ($env:APPVEYOR_BUILD_WORKER_IMAGE -eq "Ubuntu") {
+        curl -s https://codecov.io/bash > codecov
+        chmod +x codecov
+        ./codecov -f ./test/coverlet.core.tests/coverage.opencover.xml
+      }