Add docker hub ga workflow

[d-jeph]

Add Github action workflow to push docker image to docker hub

• This PR adds a Github action workflow(docker.yml) to push the webapp docker image to the tech4dev docker hub registry whenever a new release is published
• The docker image is tagged with the release version number
• The workflow only pushes the first stage of the image which is of a smaller size compared to the final image with all the stages

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 59.25%. Comparing base (177bf8b) to head (2575890).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #925 +/- ## ======================================= Coverage 59.25% 59.25% ======================================= Files 80 80 Lines 5468 5468 Branches 1309 1292 -17 ======================================= Hits 3240 3240 - Misses 2116 2200 +84 + Partials 112 28 -84 ```

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[yvonnegitau]

@d-jeph the first stage is the largest since it has the packages. The reason behind only pushing this stage is, we need NEXT_PUBLIC_XXX variables when building the code.