remove manual CI as nix integration is done

.github/workflows/ci-manual.yml

@@ -1,42 +0,0 @@
-name: On-demand multi-platform build
-
-on:
-  push:
-    branches:
-      - poc/logos-testnet-mix
-  workflow_dispatch:
-    inputs:
-      ref:
-        description: "Branch, tag, or commit SHA to build"
-        required: true
-        default: "master"
-
-jobs:
-  build:
-    strategy:
-      matrix:
-        include:
-          - platform: linux
-            runner: ubuntu-latest
-          #- platform: windows
-          #  runner: windows-latest
-          - platform: macos
-            runner: macos-latest
-    runs-on: ${{ matrix.runner }}
-
-    steps:
-      - name: Checkout requested ref
-        uses: actions/checkout@v4
-        with:
-          ref: ${{ inputs.ref || github.ref }}
-
-      - name: Build libwaku
-        run: |
-          echo "Building ref=${{ inputs.ref || github.ref }} for platform=${{ matrix.platform }}"
-          make libwaku
-
-      - name: Upload artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: libwaku-${{ matrix.platform }}
-          path: build/libwaku.*