chore: remove packages section of release-please config

Hopping that removing the package section will change the tag that
release-please will use when cutting a release. Removing the packages
section should remove the `tuxmux` prefix.

.github/release-please-config.json

@@ -15,15 +15,11 @@
     { "type": "build", "section": "Build System", "hidden": true },
     { "type": "ci", "section": "Continuous Integration", "hidden": true }
   ],
-  "packages": {
-    ".": {
-      "changelog-path": "CHANGELOG.md",
-      "release-type": "rust",
-      "bump-minor-pre-major": true,
-      "bump-patch-for-minor-pre-major": true,
-      "draft": true,
-      "prerelease": false
-    }
-  },
+  "changelog-path": "CHANGELOG.md",
+  "release-type": "rust",
+  "bump-minor-pre-major": true,
+  "bump-patch-for-minor-pre-major": true,
+  "draft": true,
+  "prerelease": false,
   "$schema": "https://raw.githubusercontent.com/googleapis/release-please/main/schemas/config.json"
 }