fix some warnings (#3886)

beacon_chain/beacon_chain_db_light_client.nim

@@ -11,8 +11,6 @@
 # protocol. See https://github.com/ethereum/consensus-specs/pull/2802
 
 import
-  # Standard library
-  std/os,
   # Status libraries
   chronicles,
   eth/db/kvstore_sqlite3,

beacon_chain/validators/keystore_management.nim

@@ -290,7 +290,7 @@ proc keyboardCreatePassword(prompt: string,
               "brute-force with automated tools. Please increase the " &
               "variety of the user characters."
         continue
-      elif password in mostCommonPasswords:
+      elif cstring(password) in mostCommonPasswords:
         echoP "The entered password is too commonly used and it would be " &
               "easy to brute-force with automated tools."
         echo ""

ncli/ncli_split_keystore.nim

@@ -1,6 +1,6 @@
 import
   std/os,
-  nimcrypto/utils, confutils, eth/keys,
+  confutils, eth/keys,
   ../beacon_chain/validators/keystore_management,
   ../beacon_chain/spec/[keystore, crypto],
   ../beacon_chain/conf