There are times where a regex isn't needed in a `strategy` block and
these changes explicitly handle that situation.

This allows the Symbol Proc format used in some `Sparkle` `livecheck`
blocks (e.g., `strategy :sparkle, &:version`) to continue working
instead of failing with a "wrong number of arguments (given 1,
expected 0)" error. This error would occur because a Symbol Proc only
only expects one argument (e.g., an `Item`, not an `Item` and a
regex/nil).

There's an argument to be made for avoiding the Symbol Proc format
for `strategy` blocks but I haven't found a way of selectively
disabling the Style/SymbolProc cop only for a `strategy` DSL method
call. That is to say, if we don't use the Symbol Proc format, `brew
style` will give a "Pass &:version as an argument to strategy instead
of a block." offense.

Besides that, this also replaces the `block` type signatures in
livecheck strategies with `T.untyped`. Sorbet doesn't know how to
handle a `Proc` with a variable number of arguments and can't be
taught how (i.e., `T.any` with a `Proc` signature for each variation
doesn't work). The aforementioned changes cause Sorbet to complain
about there being both too many and too few arguments, so the only
way to win is not to play the game. Hopefully we can restore the
`block` type signatures in the future (if upstream resolves this
years-old issue) but `T.untyped` seems to be our only option for now.