refactor(database): use never for unsupported explain drivers

Signed-off-by: memleakd <121398829+memleakd@users.noreply.github.com>

Author: memleakd

system/Database/OCI8/Builder.php

@@ -236,7 +236,7 @@ protected function compileLockForUpdate(): string
     /**
      * Ensures the current driver supports explaining Query Builder selects.
      */
-    protected function assertExplainSupported(): void
+    protected function assertExplainSupported(): never
     {
         throw new DatabaseException('OCI8 does not support explain().');
     }

system/Database/SQLSRV/Builder.php

@@ -719,7 +719,7 @@ protected function compileLockForUpdate(): string
     /**
      * Ensures the current driver supports explaining Query Builder selects.
      */
-    protected function assertExplainSupported(): void
+    protected function assertExplainSupported(): never
     {
         throw new DatabaseException('SQLSRV does not support explain().');
     }