[#78] add custom git checkout with cached files

.gitlab-ci.yml

@@ -46,7 +46,9 @@ build_win10_msvc:
     - cd 'C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\Tools\'
     - .\Launch-VsDevShell.ps1
     - cd C:\cached\vkcv-framework
-    - git pull
+    - git fetch
+    - git checkout $CI_COMMIT_BRANCH
+    - git pull $CI_COMMIT_SHA
     - git submodule init
     - git submodule update
     - mkdir debug