fix: remove dead entries from the deny.toml license allow-list

[MaximeGaudin]

Summary

• The [licenses].allow list contained OpenSSL and BSD-1-Clause, which no dependency in the graph uses (verified against the full cargo deny list output: the graph contains 0BSD, Apache-2.0, Apache-2.0 WITH LLVM-exception, BSD-2-Clause, BSD-3-Clause, BSL-1.0, CC0-1.0, CDLA-Permissive-2.0, ISC, MIT, MIT-0, MPL-2.0, MPL-2.0+, Unicode-3.0, Unlicense, Zlib — nothing else).
• Dead allow-list entries widen the accepted surface for no reason: a future dependency claiming either license would pass the check silently. Both entries are removed.

Fixes #217

Test plan

• cargo deny check passes with the entries removed (nothing depended on them).
• The check's discriminative power was verified in the opposite direction: removing the used MPL-2.0 entry makes cargo deny check licenses fail on the MPL-2.0+ crates, then passes again once restored.
• CI green on the PR