ci: GHA basic format & pre-commit (#2309)

tools/FindEigen3.cmake

@@ -78,4 +78,3 @@ else (EIGEN3_INCLUDE_DIR)
   mark_as_advanced(EIGEN3_INCLUDE_DIR)
 
 endif(EIGEN3_INCLUDE_DIR)
-

tools/libsize.py

@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 from __future__ import print_function, division
 import os
 import sys
@@ -35,4 +36,3 @@ else:
 
 with open(save, 'w') as sf:
     sf.write(str(libsize))
-

tools/mkdoc.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+# -*- coding: utf-8 -*-
 #
 #  Syntax: mkdoc.py [-I<path> ..] [.. a list of header files ..]
 #