ci: Increase Windows job timeout

The Windows job is sometimes hitting the four minute timeout, so bump it up by a
couple minutes to avoid unnecessary flakes.

Author: nicholasbishop

.github/workflows/rust.yml

@@ -140,7 +140,7 @@ jobs:
 
       - name: Run VM tests
         run: cargo xtask run --target x86_64 --ci
-        timeout-minutes: 4
+        timeout-minutes: 6
 
   # Run the build with our current nightly MSRV (specified in
   # ./msrv_toolchain.toml). This serves to check that we don't