libs2/tf: SWPROT-8720: fix Syntax warning for regex (SiliconLabsSoftware#57)

(cherry picked from commit 417b42ec16b4a7f796bce61a0f80fa59c5011e8f)
Forwarded: SiliconLabsSoftware#57
Relate-to: SiliconLabsSoftware#50
Signed-off-by: Philippe Coval <philippe.coval@silabs.com>

Author: Luisky

applications/zpc/components/zwave/zwave_transports/s2/libs/zw-libs2/TestFramework/gen_test_runner.py

@@ -8,7 +8,7 @@
 from io import open
 
 n=0
-regexp = '^void (test_[A-Za-z0-9_]+)\(.*\).*'
+regexp = r'^void (test_[A-Za-z0-9_]+)\(.*\).*'
 
 filename, file_type = os.path.splitext(sys.argv[1])