Fixes for ShellCheck errors

[atrepca]

Running the script through the shellcheck static analysis tool returns the errors below:

$ shellcheck run.sh 

In run.sh line 1:
#!/usr/bin/with-contenv bashio
^-- SC1008 (error): This shebang was unrecognized. ShellCheck only supports sh/bash/dash/ksh. Add a 'shell' directive to specify.


In run.sh line 17:
export AWS_ACCESS_KEY_ID="$(bashio::config 'aws_access_key')"
       ^---------------^ SC2155 (warning): Declare and assign separately to avoid masking return values.


In run.sh line 18:
export AWS_SECRET_ACCESS_KEY="$(bashio::config 'aws_secret_access_key')"
       ^-------------------^ SC2155 (warning): Declare and assign separately to avoid masking return values.

For more information:
  https://www.shellcheck.net/wiki/SC1008 -- This shebang was unrecognized. Sh...
  https://www.shellcheck.net/wiki/SC2155 -- Declare and assign separately to ...

SC2155 is detailed here, and SC1008 here.

ShellCheck can also run as a GitHub action.

Also removed the executable bit from other non-executables that had it.

[thomasfr]

Thank you very much. Did not know shellcheck tbh and was not aware of SC2155. So thanks for that.
If you or someone else interested in contributing, i would also accept a PR for enabling ShellCheck within Github Actions.

[atrepca]

Going to close this and fix the ShellCheck errors in #20 so the action starts with a clean state.