lower upgrade threshold (#3676)

crates/hotshot/src/traits/election/static_committee.rs

@@ -4,8 +4,7 @@
 // You should have received a copy of the MIT License
 // along with the HotShot repository. If not, see <https://mit-license.org/>.
 
-use std::collections::BTreeMap;
-use std::num::NonZeroU64;
+use std::{cmp::max, collections::BTreeMap, num::NonZeroU64};
 
 use ethereum_types::U256;
 use hotshot_types::{
@@ -183,6 +182,10 @@ impl<TYPES: NodeType> Membership<TYPES> for GeneralStaticCommittee<TYPES> {
 
     /// Get the voting upgrade threshold for the committee
     fn upgrade_threshold(&self) -> NonZeroU64 {
-        NonZeroU64::new(((self.stake_table.len() as u64 * 9) / 10) + 1).unwrap()
+        NonZeroU64::new(max(
+            (self.stake_table.len() as u64 * 9) / 10,
+            ((self.stake_table.len() as u64 * 2) / 3) + 1,
+        ))
+        .unwrap()
     }
 }