Fix typos

[hugovk]

Checklist

• I have made a material change to the repo (functionality, testing, spelling, grammar)
• I have read the [Contribution Guide] and my PR follows them.
• I updated my branch with the master branch.
• [n/a] I have added tests that prove my fix is effective or that my feature works
• [n/a] I have added necessary documentation about the functionality in the appropriate .md file
• [n/a] I have added in line documentation to the code I modified

Short description of what this PR does:

• Fix some typos
• Sendgrid -> SendGrid
• Github -> GitHub
• git -> Git
• Others found using codespell

If you have questions, please send an email to Sendgrid, or file a Github Issue in this repository.

[SendGridDX]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #616 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #616   +/-   ##
=======================================
  Coverage   84.77%   84.77%           
=======================================
  Files          35       35           
  Lines        1156     1156           
  Branches      172      172           
=======================================
  Hits          980      980           
  Misses         90       90           
  Partials       86       86

Impacted Files	Coverage Δ
sendgrid/helpers/endpoints/ip/unassigned.py	15% <ø> (ø)	⬆️
sendgrid/sendgrid.py	92% <ø> (ø)	⬆️

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[thinkingserious]

Hello @hugovk,

Thanks again for the PR!

It's HACKTOBERFEST!

We want to show our appreciation by sending you some special Hacktoberfest swag. If you have not already, could you please fill out this form so we can send it to you?

Thanks!

Team SendGrid DX

[hugovk]

Done, thank you!