Bump dotnet-t4 from 2.3.1 to 3.0.0 (#491)

Bumps [dotnet-t4](https://github.com/mono/t4) from 2.3.1 to 3.0.0.
- [Changelog](https://github.com/mono/t4/blob/main/release-steps.md)
- [Commits](mono/t4@v2.3.1...v3.0.0)

---
updated-dependencies:
- dependency-name: dotnet-t4
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.config/dotnet-tools.json

@@ -3,7 +3,7 @@
   "isRoot": true,
   "tools": {
     "dotnet-t4": {
-      "version": "2.3.1",
+      "version": "3.0.0",
       "commands": [
         "t4"
       ]