grimblast: allow decimals for --wait

[arminius-smh]

Description of changes

grimblast --wait currently only allows whole numbers, and I myself like to use it to get the cursor out of the way for screenshots, however a whole second is just a bit too unnatural too long for me and I'd like to use something like 0.5 or 0.7, so I've changed the regex to allow adding decimal numbers (I hope the regex is alright)

The usage still says [--wait N] but I initally expected N to also include decimal numbers, so not sure if this should just stay the same or if the usage should also mention that decimals are allowed, although I think that may be a bit confusing and should just stay this way

Things done

• For new programs

  • Add the program to the README table, with yourself as the
    maintainer
  • Add a README for the program itself
  • Add Makefile (and Nix derivation optionally, otherwise @fufexan will do
    it)
  • If the program is a script, add it to the
    CI checks matrix

• For changes

  • Add changes to the CHANGELOG

[fufexan]

not sure if this should just stay the same or if the usage should also mention that decimals are allowed, although I think that may be a bit confusing and should just stay this way

Let's add that clarification in the manpage.

[arminius-smh]

Let's add that clarification in the manpage.

Done 👍

[fufexan]

LGTM, thanks!