Fix windows env var ref in CI

.gitlab-ci.yml

@@ -155,7 +155,7 @@ windows:build:
       - if (Test-Path build) { Remove-Item build/ -Recurse }
       - mkdir build
       - cd build
-      - cmake -DCMAKE_GENERATOR_PLATFORM=x64 -DFTL_VERSION=$CI_COMMIT_TAG -DWITH_GNUTLS=TRUE -DGNUTLS_INCLUDE_DIR="C:/Build/bin/gnutls/lib/includes/" -DGNUTLS_LIBRARY="C:/Build/bin/gnutls/lib/libgnutls.dll.a" ..
+      - cmake -DCMAKE_GENERATOR_PLATFORM=x64 -DFTL_VERSION=%CI_COMMIT_TAG% -DWITH_GNUTLS=TRUE -DGNUTLS_INCLUDE_DIR="C:/Build/bin/gnutls/lib/includes/" -DGNUTLS_LIBRARY="C:/Build/bin/gnutls/lib/libgnutls.dll.a" ..
       - '& MSBuild.exe beyond-protocol.sln -property:Configuration=Release -nr:false -maxCpuCount'
 
 windows:test: