arrow-arith: fix 'occured' -> 'occurred' in arity.rs comments

Two comments in arrow-arith/src/arity.rs (lines 459, 508) read 'no copying occured'. Fixed to 'occurred'. Comment-only change.

Signed-off-by: SAY-5 <SAY-5@users.noreply.github.com>

Author: SAY-5

arrow-arith/src/arity.rs

@@ -456,7 +456,7 @@ mod tests {
             Some(vec![true, true, true, true, true].into()),
         );
 
-        // unwrap here means that no copying occured
+        // unwrap here means that no copying occurred
         let r2 = binary_mut(a, &b, |a, b| a + b).unwrap();
         assert_eq!(r1.unwrap(), r2.unwrap());
     }
@@ -505,7 +505,7 @@ mod tests {
             Some(vec![true, true, true, true, true].into()),
         );
 
-        // unwrap here means that no copying occured
+        // unwrap here means that no copying occurred
         let r2 = try_binary_mut(a, &b, |a, b| Ok(a + b)).unwrap();
         assert_eq!(r1.unwrap(), r2.unwrap());
     }