py : turn verify-checksum-models.py into executable (#2245)

README.md was adjusted to reflect the change.

Signed-off-by: Jiri Podivin <jpodivin@gmail.com>

README.md

@@ -640,7 +640,7 @@ Please verify the [sha256 checksums](SHA256SUMS) of all downloaded model files t
 
 ```bash
 # run the verification script
-python3 .\scripts\verify-checksum-models.py
+./scripts/verify-checksum-models.py
 ```
 
 - On linux or macOS it is also possible to run the following commands to verify if you have all possible latest files in your self-installed `./models` subdirectory:

scripts/verify-checksum-models.py

@@ -1,3 +1,5 @@
+#!/bin/env python3
+
 import os
 import hashlib