Use python3 instead of python in klc-check script

klc-check.sh

 #!/bin/bash
 
 cd kicad-library-utils/klc-check
-python check_symbol.py ../../fab.kicad_sym
+python3 check_symbol.py ../../fab.kicad_sym
 FPS=$(ls ../../fab.pretty/*.kicad_mod)
 for FP in ${FPS}
 do
-  python check_footprint.py ${FP}
+  python3 check_footprint.py ${FP}
 done