Bump nostr-sdk from d244d10 to 19a1912

Bumps [nostr-sdk](https://github.com/rust-nostr/nostr) from `d244d10` to `19a1912`.
- [Release notes](https://github.com/rust-nostr/nostr/releases)
- [Commits](rust-nostr/nostr@d244d10...19a1912)

---
updated-dependencies:
- dependency-name: nostr-sdk
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>