chore: add .osgrep to gitignore

Why:
* .osgrep cache directory was untracked and should be ignored

Changes:
* .gitignore: add .osgrep entry

Stats:
* 1 file changed
* +1 lines

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

Author: AndreiDrang

.gitignore

@@ -430,3 +430,4 @@ env/
 /.coverage
 /src/python3_capsolver.egg-info/
 /docs/_build/
+.osgrep