chore(ci): upgrade the build environment to Windows Sever 2022 and macOS 11

Author: yvt

.github/workflows/ci.yml

@@ -64,7 +64,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-20.04, macos-10.15, windows-2019]
+        os: [ubuntu-20.04, macos-11, windows-2022]
     steps:
       - name: Checkout
         uses: actions/checkout@v1
@@ -99,8 +99,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        # TODO: Add `macos-10.15` after addressing `riscv-rt` build failure
-        os: [ubuntu-20.04, windows-2019]
+        # TODO: Add `macos-11` after addressing `riscv-rt` build failure
+        os: [ubuntu-20.04, windows-2022]
         features: [all-features]
     steps:
       - name: Checkout