Commit to MSRV 1.69 for at least 1.0.0.

RELEASE-NOTES.mkdn

@@ -6,6 +6,10 @@ For an example of the changes required to port from 0.3.x to 1.0, see [the
 upgrade commit in the Keypad:GO!
 firmware](https://github.com/cbiffle/keypad-go-firmware/commit/fffdf07a6b6a4038b8dd33be396fb16fb0271d58).
 
+Minimum Supported Rust Version is still 1.69, the earliest stable toolchain that
+can build `lilos` and applications. This is getting increasingly painful,
+though, so please let me know if you actually need it.
+
 - Time-related public API is now centralized in the `time` module. In earlier
   versions this was split between `time` and `exec` for historical reasons. For
   porting existing programs, look for uses of the `sleep_*`, `with_*`, and

os/Cargo.toml

@@ -9,6 +9,7 @@ repository = "https://github.com/cbiffle/lilos/"
 keywords = ["async", "embedded", "realtime", "os"]
 categories = ["embedded"]
 readme = "README.mkdn"
+rust-version = "1.69"
 
 [package.metadata.docs.rs]
 all-features = true

rust-toolchain.toml

@@ -1,5 +1,5 @@
 [toolchain]
-channel = "1.75.0"
+channel = "1.69.0"
 targets = [ "thumbv7em-none-eabihf", "thumbv7m-none-eabi", "thumbv6m-none-eabi" ]
 profile = "minimal"
 components = [ "rustfmt", "rust-analyzer" ]