Github actions syntax: Invalid workflow file - bash

Question

I started using github actions and I am trying to let a few lines of shell script running before I create a python package. But I can't get my code to run. It always stops on the line run: | - which is odd because I have been using this exact line before before (see further down). Does anyone know what I am doing wrong?
name: Python packaging
on: [push]
jobs:
job1:
name: Update version
runs-on: ubuntu-latest
steps:
- name: checkout repo
uses: actions/checkout#v3
# ----- This is where the error occurs. Error message:
# Check failure on line 11 in .github/workflows/main.yml
# GitHub Actions / .github/workflows/main.yml
# Invalid workflow file
# You have an error in your yaml syntax on line 11
- name: Increase version
run: |
old_version=$(grep -oP '(?<=0.0.)[0-99]+' contrib/_version.py)
new_version=$(($old_version + 1))
str="__version__=\"0.0."
out="$str$new_version\""
sed -i '1s/.*/'$out'/' contrib/_version.py
job2:
name: Build and upload
needs: job1
runs-on: ubuntu-latest
strategy:
matrix:
python-version: ["3.9"]
steps:
- name: checkout repo
uses: actions/checkout#v3
- name: Set up Python ${{ matrix.python-version }}
uses: actions/setup-python#v3
with:
python-version: ${{ matrix.python-version }}
- name: Install dependencies
run: |
python -m pip install --upgrade pip setuptools wheel
python -m pip install setuptools wheel
python -m pip install --upgrade build
python -m pip install --upgrade twine
if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
- name: Create package
run: |
python3 -m build
- name: Upload to Test PyPI
env:
TWINE_USERNAME: "__token__"
TWINE_PASSWORD: ${{ secrets.PYPI_API_TOKEN }}
TWINE_REPOSITORY_URL: "https://test.pypi.org/legacy/"
run: |
twine check dist/*
twine upload --verbose --skip-existing dist/*

Answer 1

The file is in YAML syntax which highly depends on indentation.
Based on your example:
job1: and job2: must have the same indentation.
Under steps:, name: and uses: must have the same indentation.
...
name: Python packaging
on: [push]
jobs:
job1:
name: Update version
runs-on: ubuntu-latest
steps:
- name: checkout repo
uses: actions/checkout#v3
- name: Increase version
run: |
old_version=$(grep -oP '(?<=0.0.)[0-99]+' contrib/_version.py)
new_version=$(($old_version + 1))
str="__version__=\"0.0."
out="$str$new_version\""
sed -i '1s/.*/'$out'/' contrib/_version.py
job2:
name: Build and upload
# ...