cargo: Limit example dev-dependencies to arm target

Only add dev-dependendencies that are needed for the example on arm
targets as they're not needed anywhere else. This allows running the
MSRV doc and lib tests on x86 again

.github/workflows/ci.yml

@@ -29,15 +29,15 @@ jobs:
       - run: cargo test --doc --target x86_64-unknown-linux-gnu
 
   test-msrv:
-    name: build with MSRV
+    name: test with MSRV
     runs-on: "ubuntu-latest"
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
             toolchain: 1.75
-      - run: cargo build --lib --target x86_64-unknown-linux-gnu
-      - run: cargo doc --target x86_64-unknown-linux-gnu
+      - run: cargo test --lib --target x86_64-unknown-linux-gnu
+      - run: cargo test --doc --target x86_64-unknown-linux-gnu
 
   build:
     strategy:

Cargo.toml

@@ -24,6 +24,9 @@ display-interface-spi = "0.5.0"
 embedded-graphics-core = { version = "0.4.0", optional = true }
 
 [dev-dependencies]
+embedded-graphics = "0.8.0"
+
+[target.'cfg(target_arch="arm")'.dev-dependencies]
 cortex-m = { version = "0.7.2", features = ["critical-section-single-core"] }
 cortex-m-rt = "0.7.3"
 cortex-m-rtic = "1.1.4"
@@ -32,7 +35,6 @@ defmt-rtt = "0.4.0"
 panic-probe = { version = "0.3.1", features = ["print-defmt"] }
 # Used to load BMP images in various examples
 tinybmp = "0.5.0"
-embedded-graphics = "0.8.0"
 # Used by the noise_i2c examples
 rand = { version = "0.8.4", default-features = false, features = [ "small_rng" ] }
 embassy-stm32 = { version = "0.1.0", git = "https://github.com/embassy-rs/embassy", features = [ "stm32f103c8", "memory-x", "defmt", "exti", "time-driver-tim3" , "unstable-pac"]  }