remove gosu CVE's by custom building gosu with updated golang

[nathanlaceyraft]

gosu is build with a unsupported version of go (1.18)
The two support go versions that have the most CVE's resolved are 1.23.6 and 1.24.0
I felt using 1.23.6 was a safer upgrade.

This PR custom builds gosu with a currently supported go version.
And copies it into the final image.

trivy image --scanners vuln wiremock/wiremock:3.12.0
shows that we'll get rid of the following CVE's

usr/local/bin/gosu (gobinary)

Total: 58 (UNKNOWN: 0, LOW: 1, MEDIUM: 23, HIGH: 31, CRITICAL: 3)

Thanks for your consideration

• TODO

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[edminshull]

Is there a desire to get this one merged? We're also facing CVEs with golang