Cleanup: use context-manager for opening files

tools/utils/make_gl_stipple_from_xpm.py

@@ -15,12 +15,11 @@ import os
 def main():
     xpm_ls = [f for f in sys.argv[1:] if f.lower().endswith(".xpm")]
 
-    print("Converting: " + " ".join(xpm_ls))
+    print("Converting:", " ".join(xpm_ls))
 
     for xpm in xpm_ls:
-        f = open(xpm, "r")
-        data = f.read()
-        f.close()
+        with open(xpm, "r", encoding="utf-8") as fh:
+            data = fh.read()
 
         # all after first {
         data = data.split("{", 1)[1]