Bump webmock from 3.9.3 to 3.9.4

Bumps webmock from 3.9.3 to 3.9.4.

Changelog

Sourced from webmock's changelog.

3.9.4

• More intuitive error message when stubbed response body was provided as Hash

  Thanks to Ben Koshy

Commits

• 771647b Version 3.9.4
• 73e0740 Merge pull request #918 from BKSpurgeon/clarify-exception-message
• d4925b5 Merge pull request #917 from BKSpurgeon/update-documentation
• 9a7f189 Fix: Clarify exception message
• d7d1b01 Fix: README - add Bash highlighting, fix white space issue that was preventin...
• 5849ba7 Update Readme: Add top level heading for better readability
• 05d2d5d Update Readme: re-order in alphabetical order
• bde594b Merge pull request #913 from BKSpurgeon/update-documentation
• 5de9bf8 Update Readme: Add note re: support for the HTTP gem, sort in
• 262e193 Merge pull request #912 from BKSpurgeon/update-documentation
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