Auto merge of #15555 - servo:tidy-ignore-replace, r=nox

tidy: Ignore [replace]’d packages in the duplicate package lint.

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

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

<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/15555)
<!-- Reviewable:end -->

python/tidy/servo_tidy/tidy.py

@@ -330,6 +330,8 @@ def check_lock(file_name, contents):
 
     packages_by_name = {}
     for package in content.get("package", []):
+        if "replace" in package:
+            continue
         source = package.get("source", "")
         if source == r"registry+https://github.com/rust-lang/crates.io-index":
             source = "crates.io"