Update MSRV to 1.56

The winit->x11-dl 2.22.0 dependency now requires the 2021 edition which forces us to at least Rust 1.56 (at least on Linux)

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
 
     strategy:
       matrix:
-        rust: ["1.54"]
+        rust: ["1.56"]
 
     env:
       RUSTFLAGS: -D warnings
@@ -82,7 +82,7 @@ jobs:
         rust:
           - stable
           - beta
-          - "1.54"
+          - "1.56"
         os:
           - ubuntu-latest
           - macos-latest

CHANGELOG.markdown

@@ -2,7 +2,7 @@
 
 ## Unreleased
 
-- MSRV is now **1.54**. We soft-updated to this in 0.8.0 with a feature `min-const-generics`, which has now been removed (and as such, we resume having no default features).
+- MSRV is now **1.56**. We soft-updated to this to Rust 1.54 in the v0.8.0 release (with a feature `min-const-generics`), which has now been removed (and as such, we resume having no default features). Rust 1.56 is required for some indirect dependencies which now use the Rust 2021 edition
 
 - Upgraded from Dear ImGui 1.84.2 to 1.86. See [the 1.85](https://github.com/ocornut/imgui/releases/tag/v1.85) and [the 1.86](https://github.com/ocornut/imgui/releases/tag/v1.86) release notes
 

README.markdown

@@ -51,7 +51,7 @@ Additionally, the following are no longer maintained, but might work still:
 
 ## Minimum Support Rust Version (MSRV)
 
-The MSRV for `imgui-rs` and all of the backend crates is **1.54**. We update our MSRV periodically, and issue a minor bump for it.
+The MSRV for `imgui-rs` and all of the backend crates is **1.56**. We update our MSRV periodically, and issue a minor bump for it.
 
 ## Choosing a backend platform and a renderer