pubsubc installation fails

[edwardtheharris]

When building the container locally, the following error is thrown.

 => ERROR [pubsub builder 5/5] RUN go get github.com/prep/pubsubc                                                                                                                                                                                                                                                                                                                                        0.4s
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 > [pubsub builder 5/5] RUN go get github.com/prep/pubsubc:
0.373 go: go.mod file not found in current directory or any parent directory.
0.373 	'go get' is no longer supported outside a module.
0.373 	To build and install a command, use 'go install' with a version,
0.373 	like 'go install example.com/cmd@latest'
0.373 	For more information, see https://golang.org/doc/go-get-install-deprecation
0.373 	or run 'go help get' or 'go help install'.
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failed to solve: process "/bin/sh -c go get github.com/prep/pubsubc" did not complete successfully: exit code: 1