go mod init github.com/psychic-spoon/TestOpenAPI
go install github.com/deepmap/oapi-codegen/cmd/oapi-codegen@latest
Make sure the following works
oapi-codegen -version
oapi-codegen --package=main --generate types,client swagger.yaml > openapi.gen.go
oapi-codegen --package=main --generate types,server swagger.yaml > generatedserver.go