feat: new EC main class 7 introduced in BRENDA

[BenjaSanchez]

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BRENDA now includes EC main class 7 for distinguishing transport reactions (i.e. EC7.x.x.x), so some automatic/manual search for EC numbers on transport reactions might be beneficial to have further constraints on our models. @IVANDOMENZAIN thoughts? Not sure if the pipeline would need to be changed in any way, maybe the latest matching algorithm should account for this?

https://academic.oup.com/nar/article/47/D1/D542/5160988