chore: fix string formatting and ST1005 linter warning in file permission errors

[ish-g09]

Describe the bug

In pkg/config/file_permission_unix.go and pkg/config/file_permission_windows.go, the error returned by getFilePermission() is split across two concatenated string literals:

return fmt.Errorf("config file has incorrect permission flags:%s."+
	"change the file permission either to 0400 or 0600.", fi.Mode().Perm().S

Two small issues with this:

1. Missing spaces in the string: there is no space after the colon (flags:%s), and no space between the period and "change" (.change), causing words to run together in terminal output.
2. Trailing punctuation: ending the error message with a period triggers a staticcheck warning (ST1005: error strings should not end with punctuation or newlines).

Expected behavior

The error message should have clean spacing and omit trailing punctuation to follow Go conventions:

config file has incorrect permission flags: %s, change the file permission either to 0400 or 0600

Actual behavior

When an invalid file mode is encountered, the output text runs together:

config file has incorrect permission flags:-rw-r--r--.change the file permission either to 0400 or 0600.

And staticcheck reports:

pkg/config/file_permission_unix.go:30:9: error strings should not end with punctuation or newlines (ST1005)

How to Reproduce?

1. Inspect pkg/config/file_permission_unix.go:30 or pkg/config/file_permission_windows.go:30.
2. Run staticcheck ./... locally.
3. Observe the ST1005 warning.

Microcks version or git rev

main (Latest)

Install method (docker-compose, helm chart, operator, docker-desktop extension,...)

CLI

Additional information

Minor cleanup to fix terminal output formatting and ensure clean staticcheck runs.

[ish-g09]

@Harsh4902 do give your take on this