pak() fails if remote has a trailing slash

[assignUser]

Just a minor inconvenience, but similar to #150 the installation of packages fails if the e.g. github repo has a trailing slash (as often happen when copying from the browser's adressbar).

pak::pak("hedgehogqa/r-hedgehog/")  
#> Error: Can't parse remotes: hedgehogqa/r-hedgehog/
pak::pak("github::hedgehogqa/r-hedgehog/")  
#> Error: Cannot install packages:
#> * github::hedgehogqa/r-hedgehog/: missing value where TRUE/FALSE needed
packageVersion("pak")   
#> [1] '0.2.0.9000'

^{Created on 2022-01-12 by the reprex package (v2.0.1)}