ci.yml: use ubuntu-22.04

as  ubuntu-24.04 produce errors on test_cases

Author: pheiduck

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ env:
 jobs:
   test:
     name: Build and run tests (rust ${{ matrix.rust }})
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     strategy:
       matrix:
         rust:
@@ -52,7 +52,7 @@ jobs:
 
   rustfmt:
     name: rustfmt
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -69,7 +69,7 @@ jobs:
 
   clippy:
     name: clippy
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4