Investigate Renovate usage for bumping snap revisions used by charms

[sed-i]

For example in otelcol we have a fairly old version simply because we forgot about it:

https://github.com/canonical/opentelemetry-collector-operator/blob/9f982aff29d5f13e0ff14fd250e184617d254179/src/snap_management.py#L45

For example, we could come up with a custom manifest file that renovate could pick up and bump.