Support filling content field from file + update dependencies

[ILikePlayingGames]

• Add support for loading the web hook content field from a text file
• Update dependencies
• Fix jest tests not being linted

Loading content from a file instead of step output or env var is useful for cases where the content has special characters that those means cannot handle. One such case is posting ANSI coloured text, which has escape codes.

[ILikePlayingGames]

Thanks! Sorry Ive been quite busy recently so I cant fix the conflicts yet. I’ll try to look at it when I have some time.

[ILikePlayingGames]

Sorry I took a while. The conflicts are fixed now.