CI: Fix/amend be63037.

.github/workflows/build.yml

@@ -41,7 +41,7 @@ jobs:
           # CI workers do not supporter older Visual Studio versions. Fix projects to target newer available version.
           gci -recurse -filter "*.vcxproj" | ForEach-Object {
             (Get-Content $_.FullName) -Replace "<PlatformToolset>v\d{3}</PlatformToolset>","<PlatformToolset>v143</PlatformToolset>" | Set-Content -Path $_.FullName
-            (Get-Content $_.FullName) -Replace "<WindowsTargetPlatformVersion>[\d\.]+</WindowsTargetPlatformVersion>","<WindowsTargetPlatformVersion>\$(LatestTargetPlatformVersion)</WindowsTargetPlatformVersion>" | Set-Content -Path $_.FullName
+            (Get-Content $_.FullName) -Replace "<WindowsTargetPlatformVersion>[\d\.]+</WindowsTargetPlatformVersion>","<WindowsTargetPlatformVersion>\\$(LatestTargetPlatformVersion)</WindowsTargetPlatformVersion>" | Set-Content -Path $_.FullName
           }
 
       # Not using matrix here because it would inflate job count too much. Check out and setup is done for every job and that makes build times way too long.