Setup release notes build using towncrier tool

doc/newsfragments/README.md

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+This is the directory for release note fragments processed by
+[towncrier](https://github.com/hawkowl/towncrier).
+
+When making a user-visible change create a file in this directory and it will be automatically be
+included into the release note document when the next release is published.
+
+The file extension specifies the type of a change. The following are currently supported:
+
+ - .feature: a new feature.
+ - .bugfix: a bug fix.
+ - .security: a fix for security issue.
+ - .doc: a documentation improvement.
+ - .removal: a deprecation or removal of functionality.

doc/release_notes/index.md

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+Release notes
+=============
+
+[comment]: <> (towncrier release notes start)

doc/release_notes/index.template.jinja

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+{% for section, _ in sections|dictsort(by='key') %}
+{% set underline = "-" %}
+{% if section %}
+{{section}}
+{{ underline * section|length }}{% set underline = "-" %}
+
+{% endif %}
+{% if sections[section] %}
+{% for category, val in definitions|dictsort if category in sections[section]%}
+
+{{ definitions[category]['name'] }}
+{{ underline * definitions[category]['name']|length }}
+
+{% if definitions[category]['showcontent'] %}
+{% for text, values in sections[section][category]|dictsort(by='value') %}
+- {{ text }}
+{% endfor %}
+{% else %}
+- {{ sections[section][category]['']|sort|join(', ') }}
+
+
+{% endif %}
+{% if sections[section][category]|length == 0 %}
+
+No significant changes.
+
+
+{% else %}
+{% endif %}
+{% endfor %}
+{% else %}
+
+No significant changes.
+
+
+{% endif %}
+{% endfor %}

towncrier.toml

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+[tool.towncrier]
+    package = ""
+    directory = "doc/newsfragments"
+    filename = "doc/release_notes/index.md"
+    template = "doc/release_notes/index.template.jinja"
+    title_format = "\nBarrier `{version}` ( `{project_date}` )\n================================\n"
+    start_string = "[comment]: <> (towncrier release notes start)"
+    [[tool.towncrier.section]]
+        path = ""
+
+    [[tool.towncrier.type]]
+        directory = "security"
+        name = "Security fixes"
+        showcontent = false
+
+    [[tool.towncrier.type]]
+        directory = "feature"
+        name = "Features"
+        showcontent = true
+
+    [[tool.towncrier.type]]
+        directory = "bugfix"
+        name = "Bug fixes"
+        showcontent = true
+
+    [[tool.towncrier.type]]
+        directory = "doc"
+        name = "Improved Documentation"
+        showcontent = true
+
+    [[tool.towncrier.type]]
+        directory = "removal"
+        name = "Deprecations and Removals"
+        showcontent = true
+
+    [[tool.towncrier.type]]
+        directory = "misc"
+        name = "Miscellaneous"
+        showcontent = false