examples: enable more clippy categories for examples

The existing clippy findings for the examples have been addressed. This
commit removes the `allow` configuration for `rsa-irc-openssl.rs` and
`rsa-irc.rs` so that we'll catch new warnings as clippy improves. This
will help keep the examples idiomatic and free of errors.

rcgen/examples/rsa-irc-openssl.rs

@@ -1,5 +1,3 @@
-#![allow(clippy::complexity, clippy::style, clippy::pedantic)]
-
 fn main() -> Result<(), Box<dyn std::error::Error>> {
 	use rcgen::{date_time_ymd, Certificate, CertificateParams, DistinguishedName};
 	use std::fmt::Write;

rcgen/examples/rsa-irc.rs

@@ -1,5 +1,3 @@
-#![allow(clippy::complexity, clippy::style, clippy::pedantic)]
-
 fn main() -> Result<(), Box<dyn std::error::Error>> {
 	use rand::rngs::OsRng;
 	use rsa::pkcs8::EncodePrivateKey;