build_library: Clean up submit warnings.

Replace deprecated `getargspec` method with the suggested
`getfullargspec`.

BUG=None
TEST=./build_image --board=zork & flash and install image.

Change-Id: I7e6e6508b3463ff52d9c0845a19b9d53dd01b6fa
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/2589757
Tested-by: Vyshu Khota <vyshu@google.com>
Commit-Queue: Vyshu Khota <vyshu@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/build_library/cgpt.py b/build_library/cgpt.py
index ac524ae..1316abe 100755
--- a/build_library/cgpt.py
+++ b/build_library/cgpt.py
@@ -838,7 +838,7 @@
           ': $(( curr += blocks * block_size ))',
       ]
 
-  if stateful != None:
+  if stateful is not None:
     lines += fs_align_snippet + [
         'blocks=$(( numsecs - (curr + %d) / block_size ))' %
         SECONDARY_GPT_BYTES,
@@ -1581,7 +1581,7 @@
         arg, text = line.split(':', 1)
         args_help[arg.strip()] = text.strip()
 
-    argspec = inspect.getargspec(func)
+    argspec = inspect.getfullargspec(func)
     # Skip the first argument as that'll be the options field.
     args = argspec.args[1:]