Bump github.com/aws/aws-sdk-go-v2 from 1.16.11 to 1.21.2 in /extension/sigv4authextension #7099

Job	Run time
setup-environment	0s
check-codeowners	0s
checks	0s
check-collector-module-version	0s
lint-matrix	0s
build-examples	0s
correctness-metrics	0s
correctness-traces	0s
integration-tests	0s
unittest-matrix	0s
lint	2s
unittest (1.19)	2s
unittest (1.18)	1s
cross-compile	0s
build-package	0s
windows-msi	0s
publish-check	0s
publish-dev	0s
publish-stable	0s
	5s

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