FIX: error in regexp to match URLs

Summary

For #328 (closed). Insert a meaningful description for this merge request here: What is the new/changed behavior? Which bug has been fixed? Are there related issues?

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Test Environment

How to set up a test environment for manual testing?

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• All automated tests pass
• Reference related issues
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README_SETUP.md

@@ -63,10 +63,16 @@ See `build.properties.d/00_default.properties` for more information.
 
 ## Test
 
+* See [DEPENDENCIES](DEPENDENCIES#for-unit-testing) for the requirements to run the unit tests.
 * Run `make test` to compile/copy the web interface and the tests to a newly
   created `public` folder.
 * Run `make run-test-server` to start a python http server.
 * The test suite can be started with `firefox http://localhost:8000/`.
+* *On WSL (as of Feb 2024, WSL v2.0.14.0)*, port 8000 is sometimes not properly forwarded to the host
+  resulting in an unreachable test suite. Switching to a different port can be done easily
+  by using the `TEST_PORT` environment variable, e.g. with `TEST_PORT=8111 make
+  run-test-server`. Using the X11 `firefox` from within WSL always works.
+* To run the test suite non-interactively (as in CI/CD) use `make -d run-qunit`
 
 ## Clean