Bump toga from 0.4.2 to 0.4.5

Bumps [toga](https://github.com/beeware/toga) from 0.4.2 to 0.4.5.
- [Release notes](https://github.com/beeware/toga/releases)
- [Commits](beeware/toga@v0.4.2...v0.4.5)

---
updated-dependencies:
- dependency-name: toga
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

setup.cfg

@@ -30,7 +30,7 @@ install_requires =
     click
     maestral>=1.9.4.dev1
     markdown2
-    toga==0.4.2
+    toga==0.4.5
     rubicon-objc>=0.4.5
 python_requires = >=3.8