Update Toit version in CI.

Author: floitsch

.github/workflows/ci.yml

@@ -12,9 +12,9 @@ jobs:
         os: [ ubuntu-latest, windows-latest, macos-latest ]
         # The versions should contain (at least) the lowest requirement
         #    and a version that is more up to date.
-        toit-version: [ v2.0.0-alpha.170, latest ]
+        toit-version: [ v2.0.0-alpha.190, latest ]
         include:
-          - toit-version: v2.0.0-alpha.170
+          - toit-version: v2.0.0-alpha.190
             version-name: old
           - toit-version: latest
             version-name: new