revision bump due to poco upgrade

[metayan]

Fixes #23 a bit more generally.

Did

brew bump-revision -m "due to poco upgrade" $(brew uses poco)

and then something like

cd /usr/local/Homebrew/Library/Taps/pothosware/homebrew-pothos
git reset origin/master
git add .
git commit -m "revision bump due to poco upgrade"

to squash the commits into one.

Beware that brew bump-revision commits the changes into the current branch immediately. No idea what happens with changes that are already present.
Also, for now brew uses poco only lists formulae in the pothosware/homebrew-pothos tap, but it will need tweaking if/when other formulae become dependent on poco.
Might be good to check with brew bump-revision -n $(brew uses poco) first as well.