Update latest python in search

Look for python 3.13.

Author: steve-downey

Makefile

@@ -96,7 +96,7 @@ papers:
 .DEFAULT: $(_build_path)/CMakeCache.txt ## Other targets passed through to cmake
 	cmake --build $(_build_path)  --config $(CONFIG) --target $@ -- -k 0
 
-PYEXECPATH ?= $(shell which python3.12 || which python3.11 || which python3.10 || which python3.9 || which python3.8 || which python3.7 || which python3)
+PYEXECPATH ?= $(shell which python3.13 || which python3.12 || which python3.11 || which python3.10 || which python3.9 || which python3.8 || which python3)
 PYTHON ?= $(notdir $(PYEXECPATH))
 VENV := .venv
 ACTIVATE := . $(VENV)/bin/activate &&