Add changelog for #1749 (#1807) (#1821)

(cherry picked from commit 437391a0cb766ec0e7a2d87242a90b271ac31707)

Co-authored-by: Sergio Mena <[email protected]>

Author: mergify[bot]

.changelog/unreleased/bug-fixes/1749-light-client-attack-verify-all-sigs.md

@@ -0,0 +1,4 @@
+- `[evidence]` When `VerifyCommitLight` & `VerifyCommitLightTrusting` are called as part
+  of evidence verification, all signatures present in the evidence must be verified
+  ([\#1749](https://github.com/cometbft/cometbft/pull/1749))
+