Bump gitversion.tool from 5.12.0 to 6.0.3

Bumps [gitversion.tool](https://github.com/GitTools/GitVersion) from 5.12.0 to 6.0.3.
---
updated-dependencies:
- dependency-name: gitversion.tool
  dependency-type: direct:development
  update-type: version-update:major
...

Signed-off-by: dotnet-updater[bot] <100138291+dotnet-updater[bot]@users.noreply.github.com>

.config/dotnet-tools.json

@@ -21,7 +21,7 @@
       ]
     },
     "gitversion.tool": {
-      "version": "5.12.0",
+      "version": "6.0.3",
       "commands": [
         "dotnet-gitversion"
       ]