Delete header block from pull request template

[l-emele]

Description of the issue

The pull_request_template.md has the following block in the beginning:

---
name: "[A] New ontology term"
about: For including new terms into the ontology
title: Your title should make sense if said after "The issue is <your issue title>"
labels: "[A] new term, To do"
assignees: ''

---

In the template itself this renders as a nice table:

But in PRs created from this template, this looks like this:

---

name: "[A] New ontology term" about: For including new terms into the ontology title: Your title should make sense if said after "The issue is " labels: "[A] new term, To do" assignees: ''

---

It seems, this block has no real purpose. In the issue templates, this information block is used for the overview of different issue types. However, we do not have different PR types. So this block just fills up space in PRs without having any real use.

Ideas of solution

Delete this block from the PR template as it only overloads PRs.

Workflow checklist

• [ ] I am aware of the workflow for this repository