Makefile `PYS` wildcard misses every Python source under `src/gitted/`

Makefile line 9 sets PYS = $(wildcard src/**.py), but make's wildcard function treats ** as two ordinary * globs, not as a recursive globstar. With the actual layout the sources live under src/gitted/__init__.py and src/gitted/diff2msg.py, and no Python file sits directly in src/, so the pattern matches nothing and PYS expands to an empty list.

A minimal repro is make -p | grep '^PYS ', which prints PYS = (empty). Every prerequisite list that depends on PYS — ruff: $(PYS), flake8: $(PYS), mypy: $(PYS), pytest: $(PYS), test: $(RESULTS) $(PYS) — therefore drops its Python-source dependency. The targets still fire because they are listed under .PHONY, but the Makefile no longer encodes the relationship between the lint/type/test rules and the files they actually consume, and any future non-phony rule keyed on $(PYS) would silently do nothing.

The fix is to point the wildcard at the real location of the sources, e.g. PYS = $(wildcard src/gitted/*.py) (or, if other subpackages are expected later, drop to a shell find invocation), so the variable expands to the two .py files that actually exist and the prerequisite lists once again match reality.