[CI] Drop macos-11 since that is deprecated and will be removed in Q2 2024

Author: ikesyo

.github/workflows/test.yml

@@ -10,7 +10,6 @@ jobs:
       matrix:
         entry:
           # Ensure that all host can install toolchain, build project, and run tests
-          - { os: macos-11,     toolchain: wasm-5.9.1-RELEASE, wasi-backend: Node, xcode: Xcode_13.2.1.app }
           - { os: macos-12,     toolchain: wasm-5.9.1-RELEASE, wasi-backend: Node, xcode: Xcode_13.4.1.app }
           - { os: macos-13,     toolchain: wasm-5.9.1-RELEASE, wasi-backend: Node, xcode: Xcode_14.3.app }
           - { os: macos-14,     toolchain: wasm-5.9.1-RELEASE, wasi-backend: Node, xcode: Xcode_15.2.app }
@@ -58,8 +57,6 @@ jobs:
     strategy:
       matrix:
         include:
-          - os: macos-11
-            xcode: Xcode_13.2.1
           - os: macos-12
             xcode: Xcode_13.3
           - os: macos-12