aardvark-dns: trim whitespaces from error text

Noticed this while testing my aardvark-dns changes. As we capture the
full stderr it includes the final newline from the error text which will
then be returned like this to podman. However because all podman always
adds a newline to its error output on the cli it resulted in two
newlines being printed. Not a bug deal but still unnecessary and
confusing.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

Author: Luap99

src/dns/aardvark.rs

@@ -143,7 +143,7 @@ impl Aardvark {
 
         Err(std::io::Error::new(
             std::io::ErrorKind::Other,
-            format!("aardvark-dns failed to start: {}", msg),
+            format!("aardvark-dns failed to start: {}", msg.trim()),
         ))
     }