[9.x] Avoid matching 'use' in custom Stub templates

[cschra]

When using custom stubs the word 'use' is also matched outside of the import statement. With this change only the lines starting with use are taken into consideration.

Use Case:
We added an Apache License Header to the module stub and the word 'use' (L4) is used inside the license text.

<?php
/**
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace {{ namespace }};
[...]

output of the $imports variable:

array:13 [
  0 => "use this file except in compliance with the License."
  1 => " * You may obtain a copy of the License at:"
  2 => " *"
  3 => " * http://www.apache.org/licenses/LICENSE-2.0"
  4 => " *"
  5 => " * Unless required by applicable law or agreed to in writing, software"
  6 => " * distributed under the License is distributed on an "AS IS" BASIS,"
  7 => " * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied."
  8 => " * See the License for the specific language governing permissions and"
  9 => " * limitations under the License."
  10 => " */"
  11 => ""
  12 => "namespace App;"
]