Pop add pallet fails to correctly resolve relative paths when invoked inside the parachain repo.

[weezy20]

Say you create a new parachain : pop new p my-chain
Ignoring the git status for now (maybe fixed by #65 - you can meanwhile cd my-chain, git add ., git commit), if you run pop add pallet from outside my-chain, specifying runtime path as -r my-chain/runtime/src/lib.rs, the cmd works.

However, if you were to cd into my-chain and provide the runtime path as -r runtime/src/lib.rs, the cmd fails:

❯ pop add p template -r runtime/src/lib.rs
T   Pop CLI : Adding pallet "pallet-parachain-template"!
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Failed to open repository: failed to resolve path '': No such file or directory; class=Os (2); code=NotFound (-3)
Error: Workspace has uncommitted changes, aborting pallet addition