parsers: Bump base64

Version 0.21 replaced base64::decode() with an Engine trait and multiple
structs implementing it for various alphabets, various performance
profiles, etc.  It is slightly longer to import but in the end does the
very same thing.

parsers/src/util/helpers.rs

@@ -5,6 +5,7 @@
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 use crate::util::error::Error;
+use base64::{engine::general_purpose::STANDARD as Base64Engine, Engine};
 use jid::Jid;
 use std::str::FromStr;
 
@@ -58,11 +59,11 @@ pub struct Base64;
 
 impl Base64 {
     pub fn decode(s: &str) -> Result<Vec<u8>, Error> {
-        Ok(base64::decode(s)?)
+        Ok(Base64Engine.decode(s)?)
     }
 
     pub fn encode(b: &[u8]) -> Option<String> {
-        Some(base64::encode(b))
+        Some(Base64Engine.encode(b))
     }
 }
 
@@ -75,11 +76,11 @@ impl WhitespaceAwareBase64 {
             .chars()
             .filter(|ch| *ch != ' ' && *ch != '\n' && *ch != '\t')
             .collect();
-        Ok(base64::decode(&s)?)
+        Ok(Base64Engine.decode(&s)?)
     }
 
     pub fn encode(b: &[u8]) -> Option<String> {
-        Some(base64::encode(b))
+        Some(Base64Engine.encode(b))
     }
 }