update golang to 1.20 (#4783) #685

Job	Run time
Start	7s
Build integration tests	18s
Build Piper	1m 38s
Run integration tests ("(TestCNBIntegrationBindings\|TestCNBIntegrationWrongBuilderProject\|TestCNB...	1m 30s
Run integration tests ("TestCNBIntegrationPreserveFiles\b")	1m 15s
Run integration tests ("TestCNBIntegrationNPMProject")	1m 50s
Run integration tests ("TestCNBIntegrationMultiImage")	2m 51s
Run integration tests ("TestCNBIntegrationNPMCustomBuildpacksBuildpacklessProject")	1m 16s
Run integration tests ("TestCNBIntegrationNPMCustomBuildpacksFullProject")	1m 27s
Run integration tests ("TestCNBIntegrationProjectDescriptor")	1m 27s
Run integration tests ("TestCNBIntegrationPrePostBuildpacks")	1m 16s
Run integration tests ("TestGolangIntegration")	1m 56s
Run integration tests ("TestGradleIntegration")	1m 20s
Run integration tests ("TestMavenIntegration")	2m 7s
Run integration tests ("TestMTAIntegration")	1m 47s
Run integration tests ("TestTmsUploadIntegration")	52s
Run integration tests ("TestTmsExportIntegration")	45s
Run integration tests ("Test(Gauge\|GCS\|GitHub\|GitOps\|Influx\|NPM\|Piper\|Python\|Sonar\|Vault\|Karma)In...	1m 11s
Finish	1s
	24m 54s

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