Add version endpoint

[httpjamesm]

Related to #137

Add an endpoint to return the instance version as a string.

• New file src/routes/version.go:

  • Create a new file to define the version endpoint.
  • Import necessary packages.
  • Define a function GetVersion that returns the version as a string.

• Modify main.go:

  • Import the new version route.
  • Add a new route to the router for the version endpoint.

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