reorganise imports in single_char_push/inster lint

Author: AurelienFT

clippy_lints/src/methods/single_char_insert_string.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
-use rustc_ast::BorrowKind;
 use clippy_utils::source::{snippet_with_applicability, str_literal_to_char_literal};
+use rustc_ast::BorrowKind;
 use rustc_errors::Applicability;
 use rustc_hir::{self as hir, ExprKind};
 use rustc_lint::LateContext;

clippy_lints/src/methods/single_char_push_string.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
-use rustc_ast::BorrowKind;
 use clippy_utils::source::{snippet_with_applicability, str_literal_to_char_literal};
+use rustc_ast::BorrowKind;
 use rustc_errors::Applicability;
 use rustc_hir::{self as hir, ExprKind};
 use rustc_lint::LateContext;