Bump @backstage/app-defaults from 1.2.1 to 1.3.1 in /backstage

Bumps [@backstage/app-defaults](https://github.com/backstage/backstage/tree/HEAD/packages/app-defaults) from 1.2.1 to 1.3.1.
- [Release notes](https://github.com/backstage/backstage/releases)
- [Changelog](https://github.com/backstage/backstage/blob/master/packages/app-defaults/CHANGELOG.md)
- [Commits](https://github.com/backstage/backstage/commits/v1.3.1/packages/app-defaults)

---
updated-dependencies:
- dependency-name: "@backstage/app-defaults"
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

backstage/yarn.lock

@@ -2293,15 +2293,15 @@
     to-fast-properties "^2.0.0"
 
 "@backstage/app-defaults@^1.1.0":
-  version "1.2.1"
-  resolved "https://registry.yarnpkg.com/@backstage/app-defaults/-/app-defaults-1.2.1.tgz#fe974f2d919118e09ce64c5c924ce1af76c39aac"
-  integrity sha512-AA8U2fXTUS4CPDrT7anbJa5HMeU54Y7oT3GyCg9mDsAqqn09W+Jd6G86ITwNMbehDWRRS6ukhJoAE/Nbf5PX8w==
+  version "1.3.1"
+  resolved "https://registry.yarnpkg.com/@backstage/app-defaults/-/app-defaults-1.3.1.tgz#77f96a1fda3c0107ee12d6b75147204f3b1884fc"
+  integrity sha512-iZYbp5pMMi57OV+HWUo3ZOoNUXUAKVNOmjed9TnqZPO7I6QPbUWUJu9ZVZPMCEPciHcSQ0iNdifdfwmgD3IJRw==
   dependencies:
-    "@backstage/core-app-api" "^1.6.0"
-    "@backstage/core-components" "^0.12.5"
-    "@backstage/core-plugin-api" "^1.5.0"
-    "@backstage/plugin-permission-react" "^0.4.11"
-    "@backstage/theme" "^0.2.18"
+    "@backstage/core-app-api" "^1.8.0"
+    "@backstage/core-components" "^0.13.1"
+    "@backstage/core-plugin-api" "^1.5.1"
+    "@backstage/plugin-permission-react" "^0.4.12"
+    "@backstage/theme" "^0.3.0"
     "@material-ui/core" "^4.12.2"
     "@material-ui/icons" "^4.9.1"