brew 2021-05-04

• f2b2d8457 Update maintainers, manpage and completions.
• aa3e623b2 Omit warning, as brew audit already covers this
• 87cd97a52 Don't use --first-parent on core tap
• 570b62dd7 prev_f -> upstream_f
• f174d4363 extend/pathname: limit write override to a refinement
• ca11dc92c dev-cmd/generate-man-completions: update description
• 2aff9ef1e Update manpages and completions
• b9b83edc1 dev-cmd: rename brew man to brew generate-man-completions
• 4c67a8ce2 caveats: simplify non-plist return
• ef153c755 build(deps): bump codecov/codecov-action