Add shebang to fix CI error

Signed-off-by: Felix Conway <felix.conway@arm.com>
diff --git a/tests/scripts/components-platform.sh b/tests/scripts/components-platform.sh
index 824e5ff..9831b8f 100755
--- a/tests/scripts/components-platform.sh
+++ b/tests/scripts/components-platform.sh
@@ -1,3 +1,5 @@
+#!/bin/bash
+
 # components-platform.sh
 #
 # Copyright The Mbed TLS Contributors