golang: bump github.com/onsi/gomega from 1.27.4 to 1.31.1 in /tools/pipecleaner #2799

Job	Run time
tests (lint)	2m 11s
tests (config_spec)	1m 2s
tests (tools_spec)	1m 44s
tests (concourse_spec)	1m 24s
tests (manifests_spec)	2m 53s
tests (terraform_spec)	1m 16s
tests (platform_tests_spec)	1m 12s
tests (compile_platform_tests)	1m 5s
	12m 47s

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