fix signature verification for oci hosted bundles #8810

Job	Run time
Go Lint	2m 13s
Rego PR checks	12s
Generate Code	1m 24s
WASM	12s
Check Generated	2m 17s
Go Build (linux amd64)	3m 13s
Go Build (linux arm64)	2m 40s
Go Build (windows)	3m 14s
Go Build (darwin)	5m 47s
Go Test (linux)	6m 9s
Go Test (darwin)	5m 39s
Go compat build/test (ubuntu-22.04, 1.19)	3m 28s
Go compat build/test (macos-latest, 1.19)	3m 53s
Go Race Detector	7m 24s
docker image smoke test	40s
smoke-test-binaries (ubuntu-22.04, opa_linux_amd64)	19s
smoke-test-binaries (ubuntu-22.04, opa_linux_amd64_static, disabled)	21s
smoke-test-binaries (macos-latest, opa_darwin_amd64)	33s
smoke-test-binaries (windows-latest, opa_windows_amd64.exe)	42s
	50m 20s

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