Simplify the Python version check in `./wpt` (#33368)

This is more similar to our other checks, for example in localpaths.py.
diff --git a/wpt b/wpt
index eac84b6..b0e415d 100755
--- a/wpt
+++ b/wpt
@@ -2,8 +2,7 @@
 
 if __name__ == "__main__":
     import sys
-    if (sys.version_info.major < 3 or
-            (sys.version_info.major == 3 and sys.version_info.minor < 6)):
+    if sys.version_info < (3, 6):
         sys.stderr.write("wpt requires Python 3.6 or higher\n")
         sys.exit(1)