ci: add gh actions for PR labeling

[deepcharles]

Three github actions are added:

• lint-pr.yml: verify that a pr follows the conventional commit conventions (https://github.com/amannn/action-semantic-pull-request).
• pr-labeler.yml: add label to PR by reading its title (https://github.com/jimschubert/labeler-action)
• release-drafter.yml: build a release draft for each new PR that is merged with the main branch (https://github.com/release-drafter/release-drafter)

[codecov]

Codecov Report

Merging #102 (72272ba) into master (577ea32) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #102   +/-   ##
=======================================
  Coverage   86.68%   86.68%           
=======================================
  Files          41       41           
  Lines         954      954           
=======================================
  Hits          827      827           
  Misses        127      127           

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[oboulant]

LGTM
Let see how it behaves on future PRs !