Fix integration with eshell

[stac47]

Hello

Problem: When I am in eshell and I change the ruby version with chruby-use, the ruby version does not change:

  ~ $ ruby --version
  ruby 3.3.5 (2024-09-03 revision ef084cc8f4) [x86_64-linux]
  <M-x chruby-use, RET choose another version>
  ~ $ ruby --version
  ruby 3.3.5 (2024-09-03 revision ef084cc8f4) [x86_64-linux]

It seems the assignment to the buffer local variable eshell-path-env does not work. Moreover this one was deprecated in Emacs 29.1.

Solution: Use the eshell-set-path to set the eshell PATH and make sure this function is available by requiring the eshell package.

Regards