Update PR template and add checklist workflow (#162)

* Update PR template

* Add PR checklist worklfow

* Update template

Author: Alexsandruss

Diff for: .github/pull_request_template.md

@@ -0,0 +1,31 @@
+## Description
+
+_Add a comprehensive description of proposed changes_
+
+_List associated issue number(s) if exist(s): #6 (for example)_
+
+_Documentation PR (if needed): #1340 (for example)_
+
+---
+
+PR should start as a draft, then move to ready for review state after CI is passed and all applicable checkboxes are closed.
+This approach ensures that reviewers don't spend extra time asking for regular requirements.
+
+You can remove a checkbox as not applicable only if it doesn't relate to this PR in any way.
+
+Checklist to comply with **before moving PR from draft**:
+
+**PR completeness and readability**
+
+- [ ] I have reviewed my changes thoroughly before submitting this pull request.
+- [ ] I have commented my code, particularly in hard-to-understand areas.
+- [ ] I have updated the documentation to reflect the changes or created a separate PR with update and provided its number in the description, if necessary.
+- [ ] Git commit message contains an appropriate signed-off-by string _(see [CONTRIBUTING.md](https://github.com/intel/scikit-learn-intelex/blob/main/CONTRIBUTING.md#pull-requests) for details)_.
+- [ ] I have added a respective label(s) to PR if I have a permission for that.
+- [ ] I have resolved any merge conflicts that might occur with the base branch.
+
+**Testing**
+
+- [ ] I have run it locally and tested the changes extensively.
+- [ ] All CI jobs are green or I have provided justification why they aren't.
+- [ ] I have extended testing suite if new functionality was introduced in this PR.

Diff for: .github/workflows/pr-checklist.yml

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+#===============================================================================
+# Copyright 2024 Intel Corporation
+#
+# 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.
+#===============================================================================
+
+name: Check PR Checklist
+
+on:
+  pull_request:
+    types: [opened, edited, synchronize, ready_for_review, converted_to_draft]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event_name }}-${{ github.ref_name }}-${{ github.event.number || github.sha }}
+  cancel-in-progress: true
+
+jobs:
+  checklist:
+    name: Close all checkboxes before moving from draft
+    timeout-minutes: 5
+    runs-on: ubuntu-24.04
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - name: Get pull request details
+      id: pr
+      uses: actions/github-script@v7
+      with:
+        script: |
+          const pr_desc = await github.rest.pulls.get({
+            owner: context.repo.owner,
+            repo: context.repo.repo,
+            pull_number: context.payload.pull_request.number
+          });
+          core.setOutput('body', pr_desc.data.body)
+          core.setOutput('draft', pr_desc.data.draft)
+          core.setOutput('author_type', pr_desc.data.user.type)
+    - name: Check if all checkboxes are checked
+      id: checkboxes
+      env:
+        DESCRIPTION: ${{ steps.pr.outputs.body }}
+      run: |
+        UNCHECKED=$(echo "$DESCRIPTION" | grep -c '\[ \]' || true)
+        echo "unchecked=$UNCHECKED" >> $GITHUB_OUTPUT
+    - name: Fail if not all checkboxes are checked, PR is not draft and author is not a bot
+      if: ${{ (steps.pr.outputs.draft == 'false') && (steps.checkboxes.outputs.unchecked != '0') && (steps.pr.outputs.author_type != 'Bot') }}
+      run: |
+        echo "Unchecked checkboxes: ${{ steps.checkboxes.outputs.unchecked }}"
+        exit 1