fix: use grep -E instead of obsolescent egrep (#339)

Grep 3.8 and later nag when using egrep

lib/git/fallback/status_shortcuts_shell.sh

@@ -140,7 +140,7 @@ $pad$c_dark [$c_rst$e$c_dark] $c_group$relative$c_rst"
     # Export numbered variables in the order they are displayed.
     # (Exports full path, but displays relative path)
     # fetch first file (in the case of oldFile -> newFile) and remove quotes
-    local filename=$(eval echo $(echo ${stat_file[$i]} | egrep -o '^"([^\\"]*(\\.[^"]*)*)"|^[^ ]+'))
+    local filename=$(eval echo $(echo ${stat_file[$i]} | grep -E -o '^"([^\\"]*(\\.[^"]*)*)"|^[^ ]+'))
     export $git_env_char$e="$project_root/$filename"
     let e++
   done