chore(ci): exclude pinned packages from auto-updating requirements (#…

…11864)

Fix to skip over pinned packages when selecting modules to update. This
logic was accidentally removed in #11372

## Checklist
- [x] PR author has checked that all the criteria below are met
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- The PR description articulates the motivation for the change
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strategy
- The PR description notes risks associated with the change, if any
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guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
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[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
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- Title is accurate
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[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
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implications of this PR as reported in the benchmarks PR comment
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[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

scripts/freshvenvs.py

@@ -123,7 +123,7 @@ def _get_updatable_packages_implementing(modules: typing.Set[str]) -> typing.Set
         if not _venv_sets_latest_for_package(v, package):
             pinned_packages.add(package)
 
-    packages = {m for m in modules if "." not in m}
+    packages = {m for m in modules if "." not in m and m not in pinned_packages}
     return packages