tests/fmt_print: migrate to testrunner

tests/fmt_print/Makefile

@@ -4,3 +4,6 @@ include ../Makefile.tests_common
 USEMODULE += fmt
 
 include $(RIOTBASE)/Makefile.include
+
+test:
+	tests/01-run.py

tests/fmt_print/tests/01-run.py

@@ -0,0 +1,15 @@
+#!/usr/bin/env python3
+
+import os
+import sys
+
+sys.path.append(os.path.join(os.environ['RIOTBASE'], 'dist/tools/testrunner'))
+import testrunner
+
+
+def testfunc(child):
+    child.expect_exact('If you can read this:')
+    child.expect_exact('Test successful.')
+
+if __name__ == "__main__":
+    sys.exit(testrunner.run(testfunc))