Fix help flag error, remove color codes

[mszostok]

Description

Changes proposed in this pull request:

• Fix help flag error, remove color codes

Testing

1. env PLUGIN_SERVER_HOST=http://host.k3d.internal go run test/helpers/plugin_server.go
2. PLUGIN_TARGETS="flux" make build-plugins-single
3. Botkube config:

   communications:
     default-group:
       socketSlack:
         enabled: true
         channels:
           default:
             name: hakuna-matata
             bindings:
               sources: []
               executors:
                 - flux
         appToken: "xapp-1-"
         botToken: "xoxb-"
   
   
   executors:
     flux:
       botkube/flux:
         enabled: true
         config:
           log:
             level: "debug"
   
         context:
           rbac:
             group:
               type: Static
               static:
                 values: [ "system:masters" ]
   
   plugins:
     cacheDir: "/tmp/plugins"
   
     repositories:
       botkube:
         url: http://host.k3d.internal:3010/botkube.yaml
   
   settings:
     log:
       level: "debug"
       formatter: "text"
     clusterName: "labs"
     upgradeNotifier: false
   
   analytics:
     disable: true
   
   configWatcher:
     enabled: false

4. Commands to run:

   @Botkube flux delete source git --help
   

   @Botkube flux create source git webapp-latest
      --url=https://github.com/stefanprodan/podinfo 
      --branch=master 
      --interval=3m
   

   @Botkube flux delete source git webapp-latest
   

   @Botkube flux delete source git webapp-latest -s
   

Related issue(s)

Fix #1229

[pkosiec]

Works well 👌