Fix for python syntax error

 - since the file has non-ASCII characters, it can fail with a compile
   error if the doc type is not specified. This edit corrects for that.

`$ python ../SwiftPlate/testStructure.py test`

	File "testStructure.py", line 30
	SyntaxError: Non-ASCII character '\xe2' in file testStructure.py on line 30, but no encoding declared; see http://python.org/dev/peps/pep-0263/ for details

Author: idcrook

testStructure.py

@@ -1,3 +1,6 @@
+
+# -*- coding: utf-8 -*-
+
 import sys
 import os
 from os.path import join, getsize
@@ -28,4 +31,4 @@
 			print("Test Directories not found")
 			exit(1)
 print("All tests run successfully ⭐⭐⭐⭐⭐")
-exit(0)
+exit(0)