release: midi2cpp v0.3.0 - rename from midi2_cpp + midi2 v0.3.4 dependency #31

Job	Run time
Strict warnings (gcc + clang) (gcc, g++)	12s
Host tests (macos-latest)	22s
Strict warnings (gcc + clang) (clang, clang++)	11s
Host tests (ubuntu-latest)	15s
Pico SDK build (examples/rp2040-midi2)	1m 38s
Arduino compile (rp2040:rp2040:rpipico)	38s
	3m 16s

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