Ssh key issue with private repository when developing integration

I’m writing a custom integration for Home Assistant. For developing purposes, I’m using a private bitbucket python module that can be accessed using ssh and requires a SSH key. So, in the manifest.json file I added the dependency in the form:

"requirements": ["git+ssh://[email protected]/<path-to-.git>@master#<name>"]

where:
<path-to-.git> is the path to the .git file
is the module name

The problem is that Home Assistant fails to clone the repository since the HA/core does not have the SSH key. Indeed, in the registry I find this:

Home Assistant Core
2023-06-27 18:36:00.485 ERROR (SyncWorker_1) [homeassistant.util.package] Unable to install package git+ssh://[email protected]/<path-to-.git>@master#<name>: error: subprocess-exited-with-error
git clone --filter=blob:none --quiet 'ssh://****@bitbucket.org/<path-to-.git>' /tmp/pip-req-build-0gricnif did not run successfully.
Host key verification failed.

Do you know how/if is possible to store a SSH key in HA/core without using a USB drive (I’m aware of this procedure, but my Home Assistant is running on a VM).

Many thanks for any help!

Vincenzo