chore(deps): bump go.opentelemetry.io/collector/pdata from 1.20.0 to 1.21.0 in the opentelemetry group #84

Job	Run time
cover / run	53s
lint / mod	14s
lint / gen	16s
commit / lint	0s
lint / run	49s
test / run (amd64, ubuntu-latest, oldstable)	48s
test / run (amd64, macos-latest, oldstable)	54s
test / run (amd64, windows-latest, oldstable)	1m 32s
test / run (386, ubuntu-latest, oldstable)	44s
test / run (amd64, ubuntu-latest, -race, oldstable)	51s
cover / send	8s
	7m 9s

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