Use portable shebang (#!/usr/bin/env bash) for bash scripts

Replace #!/bin/bash with #!/usr/bin/env bash for portability across
systems where bash may not be installed at /bin/bash (e.g. NixOS,
some BSDs, non-standard installations).

Author: taylorhoward92

test/static_assertions/testrunner.bash

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # mess with output to confuse jenkins build failure indications because these
 # tests pass when compilation fails. Multiple pipes for OSX compatibility