ci: add r2021a

Author: scivision

.github/workflows/ci.yml

@@ -26,9 +26,9 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-22.04, windows-2022]
-        release: [R2021b, R2022a, R2022b, R2023a, R2023b, R2024a, R2024b, R2025a]
+        release: [R2021a, R2021b, R2022a, R2022b, R2023a, R2023b, R2024a, R2024b, R2025a]
 # on Linux, even R2025a needs GCC 10.x and hence Github Actions runner ubuntu-22.04.
-# R2021b, R2022a officially need Ubuntu 20.04,
+# R2021a...R2022a officially need Ubuntu 20.04,
 # which is no longer available on Github Actions
         include:
         - os: macos-latest