build(deps-dev): update requests-mock requirement from <1.2 to <1.13

Updates the requirements on [requests-mock](https://github.com/jamielennox/requests-mock) to permit the latest version.
- [Release notes](https://github.com/jamielennox/requests-mock/releases)
- [Commits](jamielennox/requests-mock@0.1.0...1.12.1)

---
updated-dependencies:
- dependency-name: requests-mock
  dependency-type: direct:development
...

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

setup.cfg

@@ -32,7 +32,7 @@ testing =
     pytest >= 6.1.2
     # mock-services is old and unmaintained. Doesn't work with newer versions
     # of requests-mock. Thus, we have to pin it down.
-    requests-mock < 1.2
+    requests-mock < 1.13
     # Python 3.12 no longer installs `setuptools` in venv
     # but mock-services depends on it for `pkg_resources`
     setuptools