feat: add #[track_caller] to unwraps for better panic messages

[m4tx]

This attribute causes the panic message to point to the location of the caller, rather than to the location where the panic is. This makes more useful panic messages, as they will point to users' codes rather than the internal Cot code.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Flag	Coverage Δ
rust	78.72% <ø> (ø)

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Files with missing lines	Coverage Δ
cot/src/db.rs	76.66% <ø> (ø)
cot/src/db/relations.rs	83.33% <ø> (ø)
cot/src/form.rs	49.23% <ø> (ø)