[style] update python style to conform to PEP 8 (#3951)

With the exception of line length set to 119 vs. 79.

Add tests/ and tools/ to py-pretty-check.

tests/scripts/thread-cert/debug.py

@@ -27,6 +27,10 @@
 #  POSSIBILITY OF SUCH DAMAGE.
 #
 
+
+from builtins import input
+
+
 class Inspector:
     """This class provides a way to inspect node status of a test case.
 
@@ -71,7 +75,7 @@ class Inspector:
         """
         node = self.test_case.nodes[nodeid]
         while True:
-            line = raw_input('> ')
+            line = input('> ')
             if not line:
                 continue
 
@@ -85,7 +89,7 @@ class Inspector:
         """ Start inspecting.
         """
         while True:
-            line = raw_input('# ')
+            line = input('# ')
             if not line:
                 continue