chore(sdk): Pin protocol buffer sources #902

Job	Run time
Validate PR title	3s
SonarCloud Scan	2m 7s
mavenverify	1m 34s
platform-integration	3m 15s
platform-xtest / resolve-versions	7s
platform-xtest / cross-client-test (main)	10m 51s
ci	1s
	17m 58s

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