Add Spring Engine

[MichaelHinrichs]

SteamDB app page links to a few games using this

https://steamdb.info/app/291150/ https://steamdb.info/app/334920/

Brief explanation of the change

Find Spring engine file types.

[SteamDB-Tracker]

After running changed rules in this pull request (this bot only tests rules.ini changes):

Changed technologies: Engine.Spring

These apps now match: (2) 291150 334920

Please confirm that all these changed apps are correct.

[Lifeismana]

not used by enough apps