ci: add runners for MPMC crossbeam implementation

Author: 0xllx0

.github/workflows/build.yml

@@ -50,6 +50,9 @@ jobs:
       - name: Run miri
         run: MIRIFLAGS=-Zmiri-ignore-leaks cargo miri test --features="alloc,defmt,mpmc_large,portable-atomic-critical-section,serde,ufmt,bytes,zeroize"
 
+      - name: Run miri (mpmc crossbeam)
+        run: MIRIFLAGS=-Zmiri-ignore-leaks cargo miri test --features="alloc,defmt,mpmc_large,mpmc_crossbeam,portable-atomic-critical-section,serde,ufmt,bytes,zeroize"
+
   # Run cargo test
   test:
     name: test
@@ -86,6 +89,9 @@ jobs:
       - name: Run cargo test
         run: cargo test --features="alloc,defmt,mpmc_large,portable-atomic-critical-section,serde,ufmt,bytes,zeroize"
 
+      - name: Run cargo test (mpmc crossbeam)
+        run: cargo test --features="alloc,defmt,mpmc_large,mpmc_crossbeam,portable-atomic-critical-section,serde,ufmt,bytes,zeroize"
+
   # Run cargo fmt --check
   style:
     name: style