Update GCS storage library to support GetObject API on gzipped objects (#6506)

Fixes #6280

vendor/go.opencensus.io/appveyor.yml

@@ -0,0 +1,24 @@
+version: "{build}"
+
+platform: x64
+
+clone_folder: c:\gopath\src\go.opencensus.io
+
+environment:
+  GOPATH: 'c:\gopath'
+  GOVERSION: '1.11'
+  GO111MODULE: 'on'
+  CGO_ENABLED: '0' # See: https://github.com/appveyor/ci/issues/2613
+
+install:
+  - set PATH=%GOPATH%\bin;c:\go\bin;%PATH%
+  - go version
+  - go env
+
+build: false
+deploy: false
+
+test_script:
+  - cd %APPVEYOR_BUILD_FOLDER%
+  - go build -v .\...
+  - go test -v .\... # No -race because cgo is disabled