Release gmailr 2.0.0

[jennybc]

Prepare for release:

• [x] git pull
• [x] Check current CRAN check results
• [x] Check if any deprecation processes should be advanced, as described in Gradual deprecation
• [x] Polish NEWS
• [x] urlchecker::url_check()
• [x] devtools::build_readme()
• [x] devtools::check(remote = TRUE, manual = TRUE)
• [x] devtools::check_win_devel()
• [x] revdepcheck::cloud_check()
• [x] Update cran-comments.md
• [x] git push
• [x] Draft blog post
• [ ] Slack link to draft blog in #open-source-comms

Submit to CRAN:

• [x] usethis::use_version('major')
• [x] devtools::submit_cran()
• [x] Approve email

Wait for CRAN...

• [x] Accepted :tada:
• [x] Add preemptive link to blog post in pkgdown news menu
• [x] usethis::use_github_release()
• [x] usethis::use_dev_version(push = TRUE)
• [x] Finish blog post
• [x] Tweet

[jennybc]

URL checks show this, but I don't think I should act on it. I don't think CRAN will see it because presumably the relevant machine doesn't have a Google user logged in (?).

Found the following (possibly) invalid URLs:
    URL: https://mail.google.com/mail/ (moved to https://mail.google.com/mail/u/0/)
      From: inst/doc/sending_messages.html
      Status: 200
      Message: OK

[jennybc]

No, CRAN does see it, so I will convert this to verbatim text I guess.

From check_win_devel():

Found the following (possibly) invalid URLs:
  URL: https://mail.google.com/mail/ (moved to https://mail.google.com/mail/u/0/)
    From: inst/doc/sending_messages.html
    Status: 301
    Message: Moved Permanently