Previously, the `RepoId` was backed by the `git2::Oid` type, which has a `Hash`
implementation that uses `std:#️⃣:Hasher::hash`. This uses a length prefixed
form for hashing.
When switching to `radicle_oid::Oid` and implementing `Hash` without the length
prefix, this subtly changed the hashes going forward.
These hashes are used in `BloomFilter`, which is the type underlying `Filter`.
This resulted in cases where a previous `Filter` that certainly contained
`rad:z3gqcJUoA1n9HaHKufZs5FCSGazv5` were suddenly reporting that they did not
contain this repository.
Changing the implementation of `Hash` for `radicle_oid::Oid` fixes this, and is
confirmed by adding the regression test in `filter.rs`.
cef0ff571d