Remove hack from depends CI workflow

[willcl-ark]

Our depends build is currently broken in a nix env as the cmake toolchain does not pass along everything needed to build correctly. See bitcoin/bitcoin#32428 for more info.

Currently we use my PR branch to build using a dependency provider. This should be removed once that is merged, or another solution found.

[willcl-ark]

Opened #5 as a possible workaround

[josibake]

just to document for my own benefit, this is the line we need to revert once there is a solution upstream in core for CMake + depends + nix: https://github.com/bitcoin-dev-tools/nix-dev-shell/blob/f175de2294cb6d7a3bfff557a768a91d93b51ede/.github/workflows/depends.yml#L31