fixup! io: Update defmt to 1.0, rename feature from "defmt_03" to "defmt"

Being explicit is necessary at this point as long as crates in the
workspace have defmt as a dependency but not as a feature.

Author: chrysn

.github/workflows/test.yml

@@ -36,7 +36,7 @@ jobs:
           cargo build
           --workspace
           --target thumbv7m-none-eabi
-          --features async,defmt-03,defmt
+          --features async,defmt-03,embedded-io/defmt
 
   msrv-1-81:
     runs-on: ubuntu-latest