build_script.py: use python3 by default (#449)

MaxDesiatov · web-flow · commit 275e4ff97149 · 2023-06-15T00:11:21.000+01:00
We're seeing sporadic CI failures, since apparently some nodes don't have `python` symlinking to a correct Python version. Changing this to `python3` will also make it consistent with the rest of the Python scripts in the Swift project.
diff --git a/build_script.py b/build_script.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # build_script.py - Build, install, and test XCTest -*- python -*-
 #
 # This source file is part of the Swift.org open source project

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-#!/usr/bin/env python`
	`1`	`+#!/usr/bin/env python3`
`2`	`2`	`# build_script.py - Build, install, and test XCTest -- python --`
`3`	`3`	`#`
`4`	`4`	`# This source file is part of the Swift.org open source project`