deps(python)(deps): update cryptography requirement (#4)

Updates the requirements on [cryptography](https://github.com/pyca/cryptography) to permit the latest version.
- [Changelog](https://github.com/pyca/cryptography/blob/main/CHANGELOG.rst)
- [Commits](pyca/cryptography@42.0.0...49.0.0)

---
updated-dependencies:
- dependency-name: cryptography
  dependency-version: 49.0.0
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements.txt

@@ -1,4 +1,4 @@
 # cogmem runtime dependencies
-cryptography>=42.0   # did:key / VC signatures / transparency log
+cryptography>=49.0.0   # did:key / VC signatures / transparency log
 fastembed>=0.3.0     # local embeddings for semantic recall
 cbor2>=5.9.0         # COSE_Sign1 / CBOR for SCITT signed statements