fix: Update Gazelle integration link in migrating.md

[hofbi]

Fix broken link in docs. Since you have a .pre-commit-config.yaml, you might want to add https://github.com/hofbi/bazel-ide/blob/0f3a63d0c3b0462726f753e3ba8cbe176acdd3ec/.pre-commit-config.yaml#L174C1-L178C62 which should prevent these links from ever getting outdated.

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Changes are visible to end-users: yes

• Searched for relevant documentation and updated as needed: yes
• Breaking change (forces users to change their own code or config): no

Test plan

• Covered by existing test cases
• New test cases added
• Manual testing; please provide instructions so we can reproduce:

[aspect-workflows]

Bazel 8 (Test)

⚠️ Buildkite build #3313 failed.

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Bazel 9 (Test)

⚠️ Buildkite build #3313 failed.

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Bazel 8 (Test)

e2e

⚠️ Buildkite build #3313 failed.

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Bazel 9 (Test)

e2e

All tests were cache hits

54 tests (100.0%) were fully cached saving 55s.

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Bazel 8 (Test)

examples/uv_pip_compile

All tests were cache hits

1 test (100.0%) was fully cached saving 444ms.

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Buildifier