Cleanup devel warnings

[schloerke]

Fixes:

* checking dependencies in R code ... NOTE
Namespaces in Imports field not imported from:
  ‘ratelimitr’ ‘rlang’ ‘withr’
  All declared Imports should be used.
* checking S3 generic/method consistency ... OK
* checking replacement functions ... OK
* checking foreign function calls ... OK
* checking R code for possible problems ... NOTE
gql_call: no visible global function definition for ‘str’
  (/home/runner/work/meetupr/meetupr/check/meetupr.Rcheck/00_pkg_src/meetupr/R/barret.R:309)
gql_call: no visible global function definition for ‘str’
  (/home/runner/work/meetupr/meetupr/check/meetupr.Rcheck/00_pkg_src/meetupr/R/barret.R:310)
Undefined global functions or variables:
  str
Consider adding
  importFrom("utils", "str")
to your NAMESPACE file.

Also:

• Added GHA for README.Rmd
• Update GHA badge location