fix: fixed potential memory leak in R_igraph_community_to_membership2()

[szhorvat]

Fixes #1362

[aviator-app]

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[aviator-app]

This pull request failed to merge: PR cannot be automatically rebased, please rebase manually to continue. Once the issues are resolved, remove the blocked label and re-queue the pull request. Note that the pull request will be automatically re-queued if it has the mergequeue label.

Additional debug info: Failed to rebase this PR onto the latest changes from the base branch. You will probably need to rebase this PR manually and resolve conflicts).

[szhorvat]

@krlmlr Why is Aviator unhappy here?

[krlmlr]

No idea, I've seen this again and again. Manually rebasing with GitHub usually does the trick.

[krlmlr]

Thanks!