CI: remove unused worflow

Signed-off-by: ZiMing Mo <msylgj@immortalwrt.org>

.github/workflows/toolchain.yml

@@ -1,64 +0,0 @@
-name: Build Toolchains
-
-on:
-  pull_request:
-    paths:
-      - '.github/workflows/build.yml'
-      - '.github/workflows/toolchain.yml'
-      - 'toolchain/**'
-  push:
-    paths:
-      - '.github/workflows/build.yml'
-      - '.github/workflows/toolchain.yml'
-      - 'toolchain/**'
-
-permissions:
-  contents: read
-
-jobs:
-  determine_targets:
-    name: Set targets
-    runs-on: ubuntu-latest
-    outputs:
-      target: ${{ steps.find_targets.outputs.target }}
-
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v3
-
-      - name: Set targets
-        id: find_targets
-        run: |
-          export TARGETS="$(perl ./scripts/dump-target-info.pl targets 2>/dev/null \
-            | sort -u -t '/' -k1,1 \
-            | awk '{ print $1 }')"
-
-          JSON='['
-          FIRST=1
-          for TARGET in $TARGETS; do
-            [[ $FIRST -ne 1 ]] && JSON="$JSON"','
-            JSON="$JSON"'"'"${TARGET}"'"'
-            FIRST=0
-          done
-          JSON="$JSON"']'
-
-           echo -e "\n---- targets ----\n"
-           echo "$JSON"
-           echo -e "\n---- targets ----\n"
-
-           echo "target=$JSON" >> $GITHUB_OUTPUT
-
-  build:
-    name: Build Target Toolchain
-    needs: determine_targets
-    permissions:
-      contents: read
-      packages: read
-    strategy:
-       fail-fast: False
-       matrix:
-         target: ${{fromJson(needs.determine_targets.outputs.target)}}
-    uses: ./.github/workflows/build.yml
-    with:
-      target: ${{ matrix.target }}
-      build_toolchain: true