Better default for PYD_LIBPYTHON

Makefile

@@ -4,7 +4,7 @@ DC ?= dmd
 export PYTHON_LIB_DIR ?= /usr/lib
 export DUB_CONFIGURATION ?= env
 export PYD_LIBPYTHON_DIR ?= /usr/lib
-export PYD_LIBPYTHON ?= python3.9
+export PYD_LIBPYTHON ?= $(shell python --version | awk '{print $$2}' | awk -F. '{print "python" $$1 "." $$2}')
 export PYD_D_VERSION_1 ?= Python_2_4_Or_Later
 export PYD_D_VERSION_2 ?= Python_2_5_Or_Later
 export PYD_D_VERSION_3 ?= Python_2_6_Or_Later