[fractal] misc: Bump MSRV to 1.60

[Julian Sparber <jsparber src gnome org>]

commit bbad1bb6b1308fdf8d1359d060bb6710e515ea0e
Author: Kévin Commaille <zecakeh tedomum fr>
Date:   Fri May 20 10:54:01 2022 +0200

    misc: Bump MSRV to 1.60
    
    Because of matrix-sdk

 Cargo.toml | 2 +-
 README.md  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/Cargo.toml b/Cargo.toml
index 220e8ca22..e8eb23a6b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,7 +3,7 @@ name = "fractal"
 version = "5.0.0-alpha"
 authors = ["Julian Sparber <julian sparber net>"]
 edition = "2018"
-rust-version = "1.58"
+rust-version = "1.60"
 
 [profile.release]
 debug = true
diff --git a/README.md b/README.md
index 1f610eef4..64e0caf13 100644
--- a/README.md
+++ b/README.md
@@ -61,7 +61,7 @@ flatpak install --user gnome-nightly org.gnome.Fractal.Devel
 
 ### Minimum Rust version
 
-To build Fractal, Rust 1.58 is required. For development, you'll need to install the nightly
+To build Fractal, Rust 1.60 is required. For development, you'll need to install the nightly
 toolchain to be able to run our pre-commit hook that validates the formatting and lints the Rust
 code.