If we prepare an environment for Linux, better also check that the os is
actually Linux.

* .github/workflows/cmake.yml
  (#Prepare Environment (Linux)): Check for the correct OS.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1927203 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/.github/workflows/cmake.yml b/.github/workflows/cmake.yml
index 9b682b7..7a480cc 100644
--- a/.github/workflows/cmake.yml
+++ b/.github/workflows/cmake.yml
@@ -107,7 +107,7 @@
           ls env: | foreach { "$($_.Name)=$($_.Value)" >> $env:GITHUB_ENV }
 
       - name: Prepare Environment (Linux)
-        if: runner.os == 'Windows'
+        if: runner.os == 'Linux'
         run: |
           # nothing yet