Add Changelog for Airflow Chart 1.3.0

[kaxil]

Adds Changelog and releases 1.3.0 of the chart

Airflow Helm Chart 1.3.0, 2021-11-08

New Features

• Chart: Add resources for cleanup and createuser jobs (Chart: add resources for cleanup and createuser jobs #19263)
• Chart: Add labels to jobs created by cleanup pods (Add Labels to jobs created by cleanup pods #19225)
• Add migration job resources (Add migration job resources #19175)
• Allow custom pod annotations to all components (18400 chart custom pod annotations #18481)
• Chart: Make PgBouncer cmd/args configurable (Chart: Make PgBouncer cmd/args configurable #18910)
• Chart: Use python 3.7 by default; support disabling triggerer (Chart: Use python 3.7 by default; support disabling triggerer #18920)

Improvements

• Chart: Increase default liveness probe timeout (Increase default liveness probe timeout #19003)
• Chart: Mount DAGs in triggerer (Chart: Mount DAGs in triggerer #18753)

Bug Fixes

• Allow Airflow UI to create worker pod via Clear > Run (Allow Airflow UI to create worker pod via Clear > Run #18272)
• Allow airflow standard images to run in openshift utilising the official helm chart Allow airflow standard images to run in openshift utilising the official helm chart #18136 (Allow airflow standard images to run in openshift utilising the official helm chart #18136 #18147)

Doc only changes

• Chart: Fix extraEnvFrom examples (Chart: Fix extraEnvFrom examples #19144)
• Chart docs: Update webserver secret key reference configuration (Update webserver secret key reference configuration #18595)
• Fix helm chart links in source install guide (Fix helm chart links in source install guide #18588)

Misc

• Chart: Update default Airflow version to 2.2.1 (Chart: Update default Airflow version to 2.2.1 #19326)
• Modernize dockerfiles builds (Modernize dockerfiles builds #19327)

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In case of fundamental code change, Airflow Improvement Proposal (AIP) is needed.
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[github-actions]

The PR is likely OK to be merged with just subset of tests for default Python and Database versions without running the full matrix of tests, because it does not modify the core of Airflow. If the committers decide that the full tests matrix is needed, they will add the label 'full tests needed'. Then you should rebase to the latest main or amend the last commit of the PR, and push it with --force-with-lease.