fix moto dev dependency specification

[jakob-keller]

Description of Change

From #1074: Replace invalid moto development dependency extra lambda with awslambda.

Assumptions

None

Checklist for All Submissions

• I have added change info to CHANGES.rst
• If this is resolving an issue (needed so future developers can determine if change is still necessary and under what conditions) (can be provided via link to issue with these details):
  • Detailed description of issue
  • Alternative methods considered (if any)
  • How issue is being resolved
  • How issue can be reproduced
• If this is providing a new feature (can be provided via link to issue with these details):
  • Detailed description of new feature
  • Why needed
  • Alternatives methods considered (if any)

Checklist when updating botocore and/or aiohttp versions

• I have read and followed CONTRIBUTING.rst
• I have updated test_patches.py where/if appropriate (also check if no changes necessary)
• I have ensured that the awscli/boto3 versions match the updated botocore version

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.11%. Comparing base (aec730a) to head (f445e2d).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1137   +/-   ##
=======================================
  Coverage   86.11%   86.11%           
=======================================
  Files          62       62           
  Lines        5933     5933           
=======================================
  Hits         5109     5109           
  Misses        824      824           

Flag	Coverage Δ
unittests	86.11% <100.00%> (ø)

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