Fix combined CI

Author: adamgreig

.github/workflows/ci.yml

@@ -29,6 +29,6 @@ jobs:
           toolchain: ${{ matrix.rust }}
           override: true
       - name: Run tests
-        run: cargo test --all
+        run: cargo test --all --exclude cortex-m-rt
 
 # FIXME: test on macOS and Windows

.github/workflows/rt-ci.yml

@@ -18,7 +18,9 @@ jobs:
           # Nightly is only for reference and allowed to fail
           - rust: nightly
             experimental: true
-
+    defaults:
+      run:
+        working-directory: cortex-m-rt
     steps:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1
@@ -55,7 +57,9 @@ jobs:
           - macOS-latest
           - windows-latest
     runs-on: ${{ matrix.os }}
-
+    defaults:
+      run:
+        working-directory: cortex-m-rt
     steps:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1