servo: Merge #13416 - Replace instances of old ServiceWorker specification URL with new one (from vigneshsarma:issue-13408); r=jdm

<!-- Please describe your changes on the following line: -->

The old specification URL is
https://slightlyoff.github.io/ServiceWorker/spec/service_worker/, which has
been replaced by the new one at https://w3c.github.io/ServiceWorker/.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #13408 (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because all the changes are in commented parts of the code.

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The old specification URL is
https://slightlyoff.github.io/ServiceWorker/spec/service_worker/ has
been replaced by the new one at https://w3c.github.io/ServiceWorker/.

Source-Repo: https://github.com/servo/servo
Source-Revision: d00639c55f9a342765483d347a3c29d4647f7411

servo/python/tidy/servo_tidy/tidy.py

@@ -69,7 +69,6 @@ WEBIDL_STANDARDS = [
     "//w3c.github.io",
     "//heycam.github.io/webidl",
     "//webbluetoothcg.github.io/web-bluetooth/",
-    "//slightlyoff.github.io/ServiceWorker/spec/service_worker/",
     # Not a URL
     "// This interface is entirely internal to Servo, and should not be" +
     " accessible to\n// web pages."