[gnome-tour] Revert "cargo: revert the change to 2021 edition"

[Jordan Petridis <jpetridis src gnome org>]

commit b33afa022c256b06c1132d84282059b942c9976d
Author: Jordan Petridis <jpetridis gnome org>
Date:   Fri Jan 28 16:56:50 2022 +0000

    Revert "cargo: revert the change to 2021 edition"
    
    This reverts commit be014fca63e168cec64eeb66de6d5383097fb2f9

 Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/Cargo.toml b/Cargo.toml
index 55109ab..b81201b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,7 +2,7 @@
 name = "gnome-tour"
 version = "40.0.0"
 authors = ["Bilal Elmoussaoui <bil elmoussaoui gmail com>"]
-edition = "2018"
+edition = "2021"
 
 
 [dependencies]