parse_env_file discard utf8 bom (#2638)

* parse_env_file discard utf8 bom

* powershell 5 may add the BOM even when explicitly using utf8

* add test + apply to GITHUB_PATH as well

* fix it

* fix powershel 5 syntax

* misc

* fixup

* fix wrong subaction

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Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>