fix: address Windows filename issues

Use underscore instead of colon since its not allowed in filenames in Windows.

This is are some of the fixes required for Windows support which gets introduced/tested in the CI overhaul PR #253.

Author: xdustinface

dash-spv/src/chain/chainlock_manager.rs

@@ -333,7 +333,7 @@ impl ChainLockManager {
         }
 
         // Store persistently
-        let key = format!("chainlock:{}", chain_lock.block_height);
+        let key = format!("chainlock_{}", chain_lock.block_height);
         let data = bincode::serialize(&chain_lock)
             .map_err(|e| StorageError::Serialization(e.to_string()))?;
         storage.store_metadata(&key, &data).await?;
@@ -414,7 +414,7 @@ impl ChainLockManager {
         let mut chain_locks = Vec::new();
 
         for height in start_height..=end_height {
-            let key = format!("chainlock:{}", height);
+            let key = format!("chainlock_{}", height);
             if let Some(data) = storage.load_metadata(&key).await? {
                 match bincode::deserialize::<ChainLock>(&data) {
                     Ok(chain_lock) => {