### Check existing issues - [x] I've verified that this request isn't described by any existing issues. ### Request Currently, any modifications to charmcraft.yaml that touch the `parts` section will cause the build to fail with the error: ``` the 'go-framework' extension is incompatible with customized charm part ``` This poses some an issue for with projects wanting to organize charms into mono repos with a separate shared module to hold common functionality, which required modifying that section of the charmcraft.yaml. They would either need to drop the go_framework extension (and potentially move away from the paas_charm library ), or deal with duplicated code in several charms in a mono repo. Additionally, this conflicts with the upcoming charmcraft 4.5 documentation on how to pack a charm in a mono repo: https://canonical.com/juju/docs/charmcraft/latest/howto/pack-a-charm-in-a-monorepo/#prerequisites. The documentation here shows a charmcraft.yaml with a custom `parts` section. Ideally, a developer should be able to use the `go_framework` extension without being locked into a specific charm part setup, so they may do any custom part logic they need when packing the charm (such as the example documentation above). ### The problem it solves Allowing the `go_framework` extension to work with customized charm parts would allow teams to use the extension and maintain monorepo projects with common code extracted into its own module for several charms to use.