GH Actions: Remove codecov token #102

Job	Run time
Check (libp2p)	1m 55s
Check (waku)	3m 50s
Rust lints (libp2p)	1m 58s
Rust lints (waku)	3m 57s
Test Suite (libp2p, ubuntu-latest)	6m 14s
Test Suite (libp2p, windows-latest)	12m 40s
Test Suite (libp2p, macos-latest)	9m 17s
Test Suite (waku, ubuntu-latest)	10m 2s
Test Suite (waku, windows-latest)	17m 58s
Test Suite (waku, macos-latest)	14m 55s
	1h 22m 46s

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