feat: add locales to allow using utf-8 characters on the console

[reubenmiller]

Install the locales package and set the appropriate encoding variables for both bash and zsh to allow users to use utf-8 characters on the console (provided their terminal also supports it!).

This is required in order to publish units (which is included in the next thin-edge.io release, 1.7.x) which often use extended characters:

tedge mqtt pub -r 'te/device/main///m/battery_reading/meta' '{
  "temperature": {
    "unit": "°C",
    "precision": "±0.1°C"
  },
  "voltage": {
    "unit": "V",
    "min": 0,
    "max": 20
  },
  "current": {
    "unit": "A"
  }
}'

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
35	0	2	35	100	4m20.661s