test against rust 1.65.0, add built-time requirements to README

Author: rursprung

.github/workflows/CI.yml

@@ -13,6 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        rust: [1.65.0, stable]
         features: ['', '--features rgb,serde']
 
     runs-on: ubuntu-latest

README.md

@@ -15,4 +15,8 @@ Note that this work is not affiliated with Adafruit.
 * `serde`: if enabled, all events implement the [serde](https://serde.rs/) `#[derive(Serialize, Deserialize)]`.
 * All events can be selected as individual features. By default, they are all selected,
   but you can opt to only select the event(s) you are interested in which will result in a small binary size.
-  If other events are received, a `ProtocolParseError::DisabledControllerDataPackageType` will be returned.
+  If other events are received, a `ProtocolParseError::DisabledControllerDataPackageType` will be returned.
+
+## Build-time Requirements
+The crate is tested against stable rust and rust 1.65.0 (which was the stable version at the time the crate has been built).
+It is possible that it works with older versions as well but this is not tested.