AlgoScan

Previously, Wallet.delete_key() always returned True regardless of
whether the address existed in the wallet. This was because the KMD
API's delete endpoint returns an empty response ({}) for both successful
deletions and 'key not found' cases.

Fix: Check if the address exists in the wallet via list_keys() before
attempting deletion. Return False immediately if the address is not
found, and only call kcl.delete_key() for addresses that actually
exist.

Fixes #472

Previously, delete_key() always returned True because it passed through
the KMD API response (empty dict == True) regardless of whether the key
actually existed in the wallet.

Now checks list_keys() first and returns False if the address is not
found, matching the documented behavior.

Closes #472

Bumps [pytest](https://github.com/pytest-dev/pytest) from 6.2.5 to 9.0.3.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](https://github.com/pytest-dev/pytest/compare/6.2.5...9.0.3)

---
updated-dependencies:
- dependency-name: pytest
  dependency-version: 9.0.3
  dependency-type: direct:production
...

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