Stac-browser should only be built on version change (security improvement)

[anayeaye]

What

We currently build the stac-browser using eoapi-cdk on every deployment regardless of changes the stac-browser version. This adds unnecessary build time and introduces more opportunities for vulnerable versions of dependencies to be installed (such as https://github.com/NASA-IMPACT/veda-architecture/issues/710#issuecomment-4184085464).

AC

• Stac browser website is only built and deployed in CICD when the stac browser version environment variable is updated.