Minor build errors (#1325)

Author: timsaucer

src/context.rs

@@ -445,7 +445,7 @@ impl PySessionContext {
             .collect::<HashMap<_, _>>();
 
         let state = self.ctx.state();
-        let dialect = state.config().options().sql_parser.dialect.as_str();
+        let dialect = state.config().options().sql_parser.dialect.as_ref();
 
         if !param_strings.is_empty() {
             query = replace_placeholders_with_strings(&query, dialect, param_strings)?;

src/dataframe.rs

@@ -548,7 +548,7 @@ impl PyDataFrame {
         self.df
             .as_ref()
             .parse_sql_expr(&expr)
-            .map(|e| PyExpr::from(e))
+            .map(PyExpr::from)
             .map_err(PyDataFusionError::from)
     }