feat(ext): remove ReasonPhrase::from_bytes_unchecked() method

BREAKING CHANGE: The `ReasonPhrase::from_bytes_unchecked()` method is
  gone. Use `from_static()` or `TryFrom` to construct one.

src/ext/h1_reason_phrase.rs

@@ -50,11 +50,12 @@ impl ReasonPhrase {
         Self(Bytes::from_static(reason))
     }
 
+    // Not public on purpose.
     /// Converts a `Bytes` directly into a `ReasonPhrase` without validating.
     ///
     /// Use with care; invalid bytes in a reason phrase can cause serious security problems if
     /// emitted in a response.
-    pub unsafe fn from_bytes_unchecked(reason: Bytes) -> Self {
+    pub(crate) fn from_bytes_unchecked(reason: Bytes) -> Self {
         Self(reason)
     }
 }

src/proto/h1/role.rs

@@ -1059,7 +1059,7 @@ impl Http1Transaction for Client {
             if let Some(reason) = reason {
                 // Safety: httparse ensures that only valid reason phrase bytes are present in this
                 // field.
-                let reason = unsafe { crate::ext::ReasonPhrase::from_bytes_unchecked(reason) };
+                let reason = crate::ext::ReasonPhrase::from_bytes_unchecked(reason);
                 extensions.insert(reason);
             }