[fractal] fractal-matrix-api: Use char type for single char patterns

[Alexandre Franke <afranke src gnome org>]

commit 715279579681bd30cb0ed2fca7903611d2f01770
Author: Zeeshan Ali <zeenix collabora co uk>
Date:   Wed Dec 12 23:05:44 2018 +0100

    fractal-matrix-api: Use char type for single char patterns
    
    This fixes this errors from clippy:
    
    ```
    error: single-character string constant used as pattern
       --> fractal-matrix-api/src/backend/media.rs:119:30
        |
    119 |         let name = url.split("/").last().unwrap_or_default();
        |                              ^^^ help: try using a char instead: `'/'`
        |
        = note: `-D clippy::single-char-pattern` implied by `-D warnings`
        = help: for further information visit 
https://rust-lang-nursery.github.io/rust-clippy/master/index.html#single_char_pattern
    ```
    
    Related: #370

 fractal-matrix-api/src/backend/media.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/fractal-matrix-api/src/backend/media.rs b/fractal-matrix-api/src/backend/media.rs
index ffb1ebe..aa9871e 100644
--- a/fractal-matrix-api/src/backend/media.rs
+++ b/fractal-matrix-api/src/backend/media.rs
@@ -117,7 +117,7 @@ pub fn get_media_url(bk: &Backend, media: String, tx: Sender<String>) -> Result<
 pub fn get_file_async(url: String, tx: Sender<String>) -> Result<(), Error> {
     let fname;
     {
-        let name = url.split("/").last().unwrap_or_default();
+        let name = url.split('/').last().unwrap_or_default();
         fname = cache_dir_path("files", name)?.clone();
     }