[ci] Remove Ubuntu 18.04 from manual distribution list and add 22.04 instead

Author: kateinoigakukun

.github/workflows/manual-distribution.yml

@@ -66,7 +66,7 @@ jobs:
               ./utils/webassembly/distribute-latest-toolchain.sh ${BRANCH:-swiftwasm-release/5.6} 5.6 "${{ github.event.inputs.toolchain_name }}"
             ;;
             *)
-              export TARGETS_TO_DIST="amazonlinux2_x86_64 ubuntu18.04_x86_64 ubuntu20.04_x86_64 ubuntu20.04_aarch64 macos_x86_64 macos_arm64"
+              export TARGETS_TO_DIST="amazonlinux2_x86_64 ubuntu20.04_x86_64 ubuntu20.04_aarch64 ubuntu22.04_x86_64 macos_x86_64 macos_arm64"
               ./utils/webassembly/distribute-latest-toolchain.sh ${BRANCH:-swiftwasm-release/$CHANNEL} "$CHANNEL" "${{ github.event.inputs.toolchain_name }}"
             ;;
           esac