ci: remove github workflow (inherited from substrate template)

.github/workflows/check.yml

-name: Check Set-Up & Build
-
-# Controls when the action will run.
-on:
-  # Triggers the workflow on push or pull request events but only for the master branch
-  push:
-    branches: [ master ]
-  pull_request:
-    branches: [ master ]
-
-  # Allows you to run this workflow manually from the Actions tab
-  workflow_dispatch:
-
-# A workflow run is made up of one or more jobs that can run sequentially or in parallel
-jobs:
-  check:
-    # The type of runner that the job will run on
-    runs-on: ubuntu-20.04
-
-    # Steps represent a sequence of tasks that will be executed as part of the job
-    steps:
-      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-      - uses: actions/checkout@v2
-
-      - name: Set-Up
-        run: sudo apt install -y cmake pkg-config libssl-dev git build-essential clang libclang-dev curl
-
-      - name: Install Rustup
-        run: |
-          curl https://sh.rustup.rs -sSf | sh -s -- -y
-          source ~/.cargo/env
-          rustup default stable
-          rustup update nightly
-          rustup update stable
-          rustup target add wasm32-unknown-unknown --toolchain nightly
-
-      - name: Check Build
-        run: |
-          SKIP_WASM_BUILD=1 cargo check --release
-
-      - name: Check Build for Benchmarking
-        run: >
-          pushd node &&
-          cargo check --features=runtime-benchmarks --release