Disable semver checks temporarily.

The check is broken due to `arbitrary` crate update (rust-fuzz/arbitrary#203).

.github/workflows/rust.yml

@@ -58,16 +58,19 @@ jobs:
     - uses: actions/checkout@v3
     - uses: stellar/actions/rust-check-git-rev-deps@main
 
-  semver-checks:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v3
-    - run: rustup update
-    - uses: stellar/binaries@v29
-      with:
-        name: cargo-semver-checks
-        version: 0.35.0
-    - run: cargo semver-checks --exclude soroban-simulation
+  # This check is currently broken due to incompatible `arbitrary` crate 
+  # update (https://github.com/rust-fuzz/arbitrary/issues/203).
+  # TODO: re-enable this as soon as the check has been fixed.
+  # semver-checks:    
+  #   runs-on: ubuntu-latest
+  #   steps:
+  #   - uses: actions/checkout@v3
+  #   - run: rustup update
+  #   - uses: stellar/binaries@v29
+  #     with:
+  #       name: cargo-semver-checks
+  #       version: 0.35.0
+  #   - run: cargo semver-checks --exclude soroban-simulation
 
   build-and-test:
     strategy: