tox.ini: Specify minimum version of click-man

click-man versions < 0.3.0 do not properly support multiple entrypoints. Since this was added to tox after 0.3.0 was released, tox should never be pulling older versions. But, let's add it here for documentation purposes.

See !1107 (comment 135187046) for some background on this.

enabled an automatic merge when the pipeline for 36746730 succeeds

merged

mentioned in commit fa4a21ce