Failed to parse `PROT` feature

[sntran]

ftpdeno/classes/FTPClient.ts

Lines 109 to 111 in a69e9bf

	this.feats = Object.fromEntries(
	FEATURES.map((feat) => [feat, discoveredFeats.includes(feat)]),
	) as FeatMatrix;

The server I tested returns "PROT C;P;" as one of its discoveredFeats, setting this.feats.PROT to false.

[nullobsi]

i believe this is non-standard as I can't find it anywhere in the RFCs, but I made a change to improve the detection