big: CI print Python3 version.

.github/workflows/ci.yml

@@ -69,6 +69,7 @@ jobs:
         run: |
           call "C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Auxiliary\Build\vcvars64.bat
           cd core\math\big\tests
+          python3 --version
           call build.bat
         timeout-minutes: 10