chore(ci): test on Noir beta 15 (#6)

Author: olehmisar

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        toolchain: [1.0.0-beta.11]
+        toolchain: [1.0.0-beta.11, 1.0.0-beta.15]
     steps:
       - name: Checkout sources
         uses: actions/checkout@v4
@@ -34,7 +34,7 @@ jobs:
       - name: Install Nargo
         uses: noir-lang/[email protected]
         with:
-          toolchain: 1.0.0-beta.11
+          toolchain: 1.0.0-beta.15
 
       - name: Run formatter
         run: nargo fmt --check