Increase compatibility with volumes on network shares

[DL6ER]

What does this implement/fix?

Also try writing lock file if we cannot acquire an exclusive lock on the file (e.g., mounted on a network share)

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Related issue or feature (if applicable): N/A

Pull request in docs with documentation (if applicable): N/A

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[yubiuser]

Will wait for feedback from pi-hole/docker-pi-hole#1715

[DL6ER]

Confirmed by two users in the linked docker issue.

[yubiuser]

Shouldn't the error be turned into a warning? It's nothing the users can fix and we proceed anyway.

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/v6-post-release-fixes-and-findings/76480/1