Fix unnecessary parens

[pronebird]

Applied a fix based on clippy suggestion

warning: unnecessary parentheses around closure body
  --> src/rule/tcp_flags.rs:46:40
   |
46 |         set.0.iter().fold(0, |acc, &x| (acc | u8::from(x)))
   |                                        ^                 ^
   |
   = note: `#[warn(unused_parens)]` on by default
help: remove these parentheses
   |
46 -         set.0.iter().fold(0, |acc, &x| (acc | u8::from(x)))
46 +         set.0.iter().fold(0, |acc, &x| acc | u8::from(x))
   |

warning: unnecessary parentheses around closure body
  --> src/rule/rule_log.rs:50:40
   |
50 |         set.0.iter().fold(0, |acc, &x| (acc | u8::from(x)))
   |                                        ^                 ^
   |
help: remove these parentheses
   |
50 -         set.0.iter().fold(0, |acc, &x| (acc | u8::from(x)))
50 +         set.0.iter().fold(0, |acc, &x| acc | u8::from(x))
   |

warning: `pfctl` (lib) generated 2 warnings (run `cargo fix --lib -p pfctl` to apply 2 suggestions)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.45s

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This change is 

[hulthe]

Thanks!