Drop 5.5, 5.6 support

Author: kateinoigakukun

.github/workflows/test.yml

@@ -16,14 +16,10 @@ jobs:
           - { os: ubuntu-22.04, toolchain: wasm-5.9-SNAPSHOT-2024-01-12-a, wasi-backend: Node }
 
           # Ensure that test succeeds with all toolchains and wasi backend combinations
-          - { os: ubuntu-20.04, toolchain: wasm-5.5.0-RELEASE, wasi-backend: Node }
-          - { os: ubuntu-20.04, toolchain: wasm-5.6.0-RELEASE, wasi-backend: Node }
           - { os: ubuntu-20.04, toolchain: wasm-5.7.3-RELEASE, wasi-backend: Node }
           - { os: ubuntu-20.04, toolchain: wasm-5.8.0-RELEASE, wasi-backend: Node }
-          - { os: ubuntu-20.04, toolchain: wasm-5.6.0-RELEASE, wasi-backend: Wasmer }
           - { os: ubuntu-20.04, toolchain: wasm-5.7.3-RELEASE, wasi-backend: Wasmer }
           - { os: ubuntu-20.04, toolchain: wasm-5.8.0-RELEASE, wasi-backend: Wasmer }
-          - { os: ubuntu-20.04, toolchain: wasm-5.6.0-RELEASE, wasi-backend: MicroWASI }
           - { os: ubuntu-20.04, toolchain: wasm-5.7.3-RELEASE, wasi-backend: MicroWASI }
           - { os: ubuntu-20.04, toolchain: wasm-5.8.0-RELEASE, wasi-backend: MicroWASI }
 
@@ -45,7 +41,6 @@ jobs:
       - run: make bootstrap
       - run: make test
       - run: make unittest
-        if: ${{ startsWith(matrix.toolchain, 'wasm-5.7.') }}
       - name: Check if SwiftPM resources are stale
         run: |
           make regenerate_swiftpm_resources