Style: use StringComparison IgnoreCase instead of ToLowerInvariant

src/Neo.CLI/CLI/MainService.Tools.cs

@@ -75,7 +75,7 @@ private void OnParseCommand(string value)
         [ParseFunction(".nef file path to content base64")]
         private string? NefFileToBase64(string path)
         {
-            if (Path.GetExtension(path).ToLower() != ".nef") return null;
+            if (!Path.GetExtension(path).Equals(".nef", StringComparison.CurrentCultureIgnoreCase)) return null;
             if (!File.Exists(path)) return null;
             return Convert.ToBase64String(File.ReadAllBytes(path));
         }

src/Neo.CLI/CLI/MainService.Wallet.cs

@@ -86,7 +86,7 @@ private void OnCloseWalletCommand()
         [ConsoleCommand("upgrade wallet", Category = "Wallet Commands")]
         private void OnUpgradeWalletCommand(string path)
         {
-            if (Path.GetExtension(path).ToLowerInvariant() != ".db3")
+            if (!Path.GetExtension(path).Equals(".db3", StringComparison.InvariantCultureIgnoreCase))
             {
                 ConsoleHelper.Warning("Can't upgrade the wallet file. Check if your wallet is in db3 format.");
                 return;

src/Neo/Wallets/NEP6/NEP6WalletFactory.cs

@@ -20,7 +20,7 @@ class NEP6WalletFactory : IWalletFactory
 
         public bool Handle(string path)
         {
-            return Path.GetExtension(path).ToLowerInvariant() == ".json";
+            return Path.GetExtension(path).Equals(".json", StringComparison.InvariantCultureIgnoreCase);
         }
 
         public Wallet CreateWallet(string name, string path, string password, ProtocolSettings settings)

src/Plugins/SQLiteWallet/SQLiteWalletFactory.cs

@@ -26,7 +26,7 @@ public SQLiteWalletFactory()
 
         public bool Handle(string path)
         {
-            return GetExtension(path).ToLowerInvariant() == ".db3";
+            return GetExtension(path).Equals(".db3", StringComparison.InvariantCultureIgnoreCase);
         }
 
         public Wallet CreateWallet(string name, string path, string password, ProtocolSettings settings)