Update dependency certora-cli to v8.6.1 (OpenZeppelin#6146)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>

Author: renovate[bot]

fv-requirements.txt

@@ -1,4 +1,4 @@
-certora-cli==8.3.1
+certora-cli==8.6.1
 # File uses a custom name (fv-requirements.txt) so that it isn't picked by Netlify's build
 # whose latest Python version is 0.3.8, incompatible with most recent versions of Halmos
 halmos==0.3.3

fv/specs/ERC721.spec

@@ -682,7 +682,7 @@ rule setApprovalForAll(env e, address operator, bool approved) {
     bool success = !lastReverted;
 
     // liveness
-    assert success <=> operator != 0;
+    assert success <=> (owner != 0 && operator != 0);
 
     // effect
     assert success => isApprovedForAll(owner, operator) == approved;