Update mercurial to non-yanked 6.7.4

Mercurial version 6.7rc0-6.7.3 have been yanked on PyPI with message:

```
critical bug that can destroy the changelog of repositories
```

lib/galaxy/dependencies/pinned-requirements.txt

@@ -105,7 +105,7 @@ markdown-it-py==3.0.0 ; python_version >= "3.8" and python_version < "3.13"
 markdown==3.6 ; python_version >= "3.8" and python_version < "3.13"
 markupsafe==2.1.5 ; python_version >= "3.8" and python_version < "3.13"
 mdurl==0.1.2 ; python_version >= "3.8" and python_version < "3.13"
-mercurial==6.7.3 ; python_version >= "3.8" and python_version < "3.13"
+mercurial==6.7.4 ; python_version >= "3.8" and python_version < "3.13"
 mistune==3.0.2 ; python_version >= "3.8" and python_version < "3.13"
 mrcfile==1.5.0 ; python_version >= "3.8" and python_version < "3.13"
 msal==1.28.0 ; python_version >= "3.8" and python_version < "3.13"