Remove deprecated DBALException factory methods

UPGRADE.md

 # Upgrade to 3.0
 
+## BC BREAK: Removed DBALException factory methods
+
+The following factory methods of the DBALException class have been removed:
+
+1. `DBALException::invalidPlatformSpecified()`.
+2. `DBALException::invalidPdoInstance()`.
+
 ## BC BREAK: PDO-based driver classes are moved under the PDO namespace
 
 The following classes have been renamed:

src/DBALException.php

@@ -28,16 +28,6 @@ class DBALException extends Exception
         return new self(sprintf("Operation '%s' is not supported by platform.", $method));
     }
 
-    /**
-     * @deprecated Use {@link invalidPlatformType()} instead.
-     */
-    public static function invalidPlatformSpecified(): self
-    {
-        return new self(
-            "Invalid 'platform' option specified, need to give an instance of " . AbstractPlatform::class . '.'
-        );
-    }
-
     /**
      * @param mixed $invalidPlatform
      */
@@ -82,19 +72,6 @@ class DBALException extends Exception
         );
     }
 
-    /**
-     * @deprecated Passing a PDO instance in connection parameters is deprecated.
-     *
-     * @return DBALException
-     */
-    public static function invalidPdoInstance()
-    {
-        return new self(
-            "The 'pdo' option was used in DriverManager::getConnection() but no " .
-            'instance of PDO was given.'
-        );
-    }
-
     /**
      * @param string|null $url The URL that was provided in the connection parameters (if any).
      *