CI: Add missing/new Rust tests/examples from RIOT OS

.github/workflows/test.yml

@@ -23,7 +23,7 @@ jobs:
         # This is the subset of `make -f makefiles/app_dirs.inc.mk
         # info-applications` that is probably relevant; more is covered when
         # riot-wrappers are updated in RIOT.
-        example: [examples/rust-hello-world, examples/rust-gcoap, tests/rust_minimal]
+        example: [examples/rust-hello-world, examples/rust-gcoap, tests/rust-async, tests/rust_minimal, tests/rust_libs]
         board: [native, sltb001a, samr21-xpro, stk3700]
     steps:
     # common steps start here