Fix CI upload assets tag matching
Fix CI upload assets tag matching

The previous version would search for the last tag by matching the
beginning of the tag name. By explicitly searching for the trailing `"`
with grep, an exact tag match is now enforced.

Since releases like v1.2.3 always match the beginning of their RCs
(v1.2.3-rc4), this makes sure that the assets aren't pushed to the
previous release.
jwilm/alacritty,alacritty/alacritty,jwilm/alacritty,jwilm/alacritty,jwilm/alacritty,alacritty/alacritty