PSA: Mlem is not open-source

Mlem is licensed under the Commons Clause, which prohibits commercial use, even though the project advertises itself as "open source".

The maintainers have refused to accept PRs that change the wording to "source-available", edited comments and locked threads about the topic:

• https://github.com/mormaer/Mlem/issues/259
• https://github.com/mormaer/Mlem/issues/170
• https://github.com/mormaer/Mlem/pull/240