fix: Use std::path::MAIN_SEPARATOR to determine completion

Refs #1439

helix-term/src/ui/mod.rs

@@ -283,7 +283,7 @@ pub mod completers {
         let is_tilde = input.starts_with('~') && input.len() == 1;
         let path = helix_core::path::expand_tilde(Path::new(input));
 
-        let (dir, file_name) = if input.ends_with('/') {
+        let (dir, file_name) = if input.ends_with(std::path::MAIN_SEPARATOR) {
             (path, None)
         } else {
             let file_name = path

helix-term/src/ui/prompt.rs

@@ -473,7 +473,7 @@ impl Component for Prompt {
                 }
             }
             key!(Enter) => {
-                if self.selection.is_some() && self.line.ends_with('/') {
+                if self.selection.is_some() && self.line.ends_with(std::path::MAIN_SEPARATOR) {
                     self.completion = (self.completion_fn)(&self.line);
                     self.exit_selection();
                 } else {