Bump github.com/onsi/gomega from 1.30.0 to 1.31.0 #288

Job	Run time
Check whether tests need to be run based on diff	14s
Verify docs and spelling	42s
Go benchmark test	4m 42s
Golangci-lint (macos-latest)	11m 9s
Build Antrea and antctl binaries	10m 3s
Golangci-lint (ubuntu-latest)	7m 39s
Integration test	10m 30s
Unit test (ubuntu-latest)	6m 17s
Unit test (windows-2022)	11m 4s
Check tidy, code generation and manifest	6m 1s
Build Antrea Windows binaries	1m 55s
	1h 10m 16s

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