fix: remove self-referencing .gitignore entry (#19)

The .gitignore file was ignoring itself, causing release-plz to fail
with "uncommitted changes" errors since tracked files matched gitignore
patterns.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: darioalessandro

.gitignore

@@ -1,3 +1,2 @@
 .DS_Store
 target
-.gitignore