Revert "fix: pin musl 1.2.5 for DNS fixes" (#6222)

Reverts openai/codex#6189

.github/actions/setup-musl-1_2_5/action.yml

@@ -1,47 +0,0 @@
-name: Setup musl 1.2.5 toolchain
-description: Install musl 1.2.5 from source and configure the linker for the requested target.
-inputs:
-  target:
-    description: Cargo target triple that requires musl (e.g., x86_64-unknown-linux-musl).
-    required: true
-runs:
-  using: composite
-  steps:
-    - name: Install musl 1.2.5
-      shell: bash
-      env:
-        MUSL_VERSION: 1.2.5
-        MUSL_PREFIX: /opt/musl-1.2.5
-        DEBIAN_FRONTEND: noninteractive
-      run: |
-        set -euo pipefail
-        sudo apt-get -y update -o Acquire::Retries=3
-        sudo apt-get -y install --no-install-recommends build-essential curl pkg-config
-
-        curl -sSfL --retry 3 --retry-delay 1 "https://musl.libc.org/releases/musl-${MUSL_VERSION}.tar.gz" -o /tmp/musl.tar.gz
-        tar -xf /tmp/musl.tar.gz -C /tmp
-
-        pushd "/tmp/musl-${MUSL_VERSION}"
-        ./configure --prefix="${MUSL_PREFIX}"
-        make -j"$(nproc)"
-        sudo make install
-        popd
-
-        echo "${MUSL_PREFIX}/bin" >> "$GITHUB_PATH"
-        musl_gcc="${MUSL_PREFIX}/bin/musl-gcc"
-        "${musl_gcc}" --version
-
-        case "${{ inputs.target }}" in
-          x86_64-unknown-linux-musl)
-            echo "CC_x86_64_unknown_linux_musl=${musl_gcc}" >> "$GITHUB_ENV"
-            echo "CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_LINKER=${musl_gcc}" >> "$GITHUB_ENV"
-            ;;
-          aarch64-unknown-linux-musl)
-            echo "CC_aarch64_unknown_linux_musl=${musl_gcc}" >> "$GITHUB_ENV"
-            echo "CARGO_TARGET_AARCH64_UNKNOWN_LINUX_MUSL_LINKER=${musl_gcc}" >> "$GITHUB_ENV"
-            ;;
-          *)
-            echo "Unsupported musl target '${{ inputs.target }}'" >&2
-            exit 1
-            ;;
-        esac