Update pkgdown GitHub Action

[yutannihilation]

pkgdown action now fails with the following error. It seems we now need to configure username and email explicitly (c.f. r-lib/actions#135). Since the latest pkgdown.yml already handles this and it contains some other improvements, I copied it and added some tweaks (including publish event, installing binary packages, and installing tidytemplate).

https://github.com/tidyverse/ggplot2/runs/921163458#step:7:520:

── Commiting updated site ──────────────────────────────────────────────────────
Running git add -A .
Running git commit --allow-empty -m \
  'Built site for ggplot2: 3.3.2.9000@8f7b03c'

*** Please tell me who you are.

Run

  git config --global user.email "[email protected]"
  git config --global user.name "Your Name"

to set your account's default identity.
Omit --global to set the identity only in this repository.

fatal: unable to auto-detect email address (got 'runner@Mac-1595979566438.(none)')

Error: System command 'git' failed, exit status: 128, stdout & stderr were printed

[yutannihilation]

@karawoo
Could you approve this as well? Sorry, I failed to address the pkgdown failure in #4147...
Confirmed this works on my forked repo:
https://github.com/yutannihilation/ggplot2/runs/921446697?check_suite_focus=true

[yutannihilation]

Thanks!