Remove clippy workaround introduced

Remove clippy workaround introduced to avoid false positive checks
in the file `lib/src/config/config_file/mod.rs`. This can be
removed now since the issue that introduced it in clippy land is
already closed.
This closes #378.

lib/src/config/config_file/mod.rs

@@ -238,10 +238,6 @@ impl FromStr for Network {
     type Err = ();
 
     fn from_str(s: &str) -> Result<Network, ()> {
-        // Fixme: Introduced this to workaround false positives in clippy
-        // as documented here:
-        // https://github.com/rust-lang/rust-clippy/issues/7863
-        #[allow(clippy::match_str_case_mismatch)]
         Ok(match s.to_lowercase().as_str() {
             "main" => Network::Main,
             "test" => Network::Test,