Add metadata to automatic specs.json generation (openvinotoolkit#1284)

<!-- Contributing guide:
https://github.com/openvinotoolkit/datumaro/blob/develop/CONTRIBUTING.md
-->

### Summary

Closes openvinotoolkit#1276.

Additionally, updates the license header in PR template.

### Checklist
<!-- Put an 'x' in all the boxes that apply -->
- [ ] I have added unit tests to cover my changes.​
- [ ] I have added integration tests to cover my changes.​
- [ ] I have added the description of my changes into
[CHANGELOG](https://github.com/openvinotoolkit/datumaro/blob/develop/CHANGELOG.md).​
- [ ] I have updated the
[documentation](https://github.com/openvinotoolkit/datumaro/tree/develop/docs)
accordingly

### License

- [x] I submit _my code changes_ under the same [MIT
License](https://github.com/openvinotoolkit/datumaro/blob/develop/LICENSE)
that covers the project.
  Feel free to contact the maintainers if that's a concern.
- [ ] I have updated the license header for each file (see an example
below).

```python
# Copyright (C) 2023 Intel Corporation
#
# SPDX-License-Identifier: MIT
```

---------

Signed-off-by: Ilya Trushkin <[email protected]>

.github/pull_request_template.md

@@ -31,7 +31,7 @@ not fully covered by unit tests or manual testing can be complicated. -->
 - [ ] I have updated the license header for each file (see an example below).
 
 ```python
-# Copyright (C) 2023 Intel Corporation
+# Copyright (C) 2024 Intel Corporation
 #
 # SPDX-License-Identifier: MIT
 ```