Bump golang version / set to latest golang alpine image

[NorskNoobing]

Description of the change

Sets the golang image in the DOCKERFILE to golang:alpine. This makes it so it always uses the latest golang alpine version, so the image building process won't break each time the golang package dependencies are updated.

Type of change

• Refactoring (no change in functionality)
• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation or Development tools (readme, specs, tests, code formatting)

Checklists

Development

• Prettier was run on frontend
• go fmt was run on backend

(if new config variable was added):

• Configuration documentation was updated
• Docker Compose example file was updated (for required variables with no default)

(if new dependency was added):

• New dependencies have been audited and are justified
• Development documentation has been updated

(if database schema was updated):

• New database migrations have been generated with migrate tool
• Migrations have been tested in both directions (cleanly migrates up and down)

Paperwork

• This pull request has a descriptive title and information useful to a reviewer
• AUTHORS.txt was updated if there are new contributors (welcome!)

Code review

• Security impacts of this change have been considered

[NorskNoobing]

This solves #60