Replace --show-current in open-pr-github to support older versions of Git

[salcode]

The git branch --show-current command was only introduced in Git 2.22.0, which was released 2019-06-07.

If you’re running an older version of Git, this command will fail. Instead we can use

git rev-parse --abbrev-ref HEAD

which gives the same result as git branch --show-current but is supported in much older versions of GIt.

Change to Make

We want to change git branch --show-current in this line

salcode-git/gitconfig

Line 20 in a532c81

open \"$(git ls-remote --get-url $(git config --get branch.$(git branch --show-current).remote) \

and this line

salcode-git/gitconfig

Line 24 in a532c81

git config --get branch.$(git branch --show-current).merge | cut -d '/' -f 3- \

to git rev-parse --abbrev-ref HEAD