Bump go.opentelemetry.io/otel/sdk from 1.19.0 to 1.21.0 in /extension/zpagesextension #821

Job	Run time
govulncheck	1m 12s
setup-environment	32s
checks	26s
unittest-matrix (~1.21.3)	1m 20s
cross-build-collector (darwin, amd64)	16s
lint	1m 25s
unittest-matrix (~1.20.10)	1m 15s
test-coverage	1m 25s
cross-build-collector (darwin, arm64)	13s
cross-build-collector (linux, 386)	7s
cross-build-collector (linux, amd64)	11s
cross-build-collector (linux, arm64)	7s
cross-build-collector (linux, ppc64le)	14s
cross-build-collector (linux, arm, 7)	12s
cross-build-collector (linux, s390x)	7s
cross-build-collector (windows, 386)	7s
cross-build-collector (windows, amd64)	13s
unittest	1s
	9m 23s

Provide feedback