typo fixes all over the place

found and semi-manually replaced by using:
 codespell -L mut -L crate -i 3 -w

Mostly in comments, but also email notification and two occurrences
of misspelled  'reserved' struct member, which where not used and
cargo build did not complain about the change, soo ...

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/api2/config/tape_encryption_keys.rs

@@ -119,7 +119,7 @@ pub fn change_passphrase(
     let kdf = kdf.unwrap_or_default();
 
     if let Kdf::None = kdf {
-        bail!("Please specify a key derivation  funktion (none is not allowed here).");
+        bail!("Please specify a key derivation function (none is not allowed here).");
     }
 
     let _lock = open_file_locked(
@@ -187,7 +187,7 @@ pub fn create_key(
     let kdf = kdf.unwrap_or_default();
 
     if let Kdf::None = kdf {
-        bail!("Please specify a key derivation  funktion (none is not allowed here).");
+        bail!("Please specify a key derivation function (none is not allowed here).");
     }
 
     let (key, mut key_config) = KeyConfig::new(password.as_bytes(), kdf)?;