fix(ci): adjust crate downgrades for test-core MSRV (#7346)

.github/workflows/test-core.yml

@@ -94,6 +94,8 @@ jobs:
           cargo update -p ignore --precise 0.4.18
           cargo update -p raw-window-handle --precise 0.5.0
           cargo update -p cargo_toml:0.15.3 --precise 0.15.2
+          cargo update -p zbus --precise 3.13.0
+          cargo update -p zbus_names --precise 2.5.0
 
       - name: test
         run: cargo test --target ${{ matrix.platform.target }} ${{ matrix.features.args }}