Bump aquasecurity/trivy-action from 0.17.0 to 0.21.0 #303

Job	Run time
Verify docs and spelling	47s
Check whether tests need to be run based on diff	13s
Golangci-lint (ubuntu-latest)	7m 55s
Go benchmark test	4m 52s
Build Antrea and antctl binaries	10m 12s
Golangci-lint (macos-latest)	17m 7s
Integration test	10m 47s
Unit test (ubuntu-latest)	6m 41s
Unit test (windows-2022)	11m 44s
Check tidy, code generation and manifest	5m 44s
Build Antrea Windows binaries	1m 56s
	1h 17m 58s

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