ci: Disable GitHub Actions builds

Prepares a migration to self-hosted CI.

.github/workflows/build.yml

@@ -1,33 +0,0 @@
-name: build
-
-on:
-  # Trigger the workflow on push or pull request,
-  # but only for the master branch
-  push:
-    branches:
-      - master
-  pull_request:
-    branches:
-      - master
-
-jobs:
-  build:
-    runs-on: [ubuntu-latest]
-    container:
-      image: leoetlino/botw-build:1.0.0
-
-    steps:
-    - uses: actions/checkout@v2
-    - run: git submodule update --init --recursive
-    - run: mkdir build
-    - name: Run CMake
-      run: cmake -GNinja -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_TOOLCHAIN_FILE=../ToolchainNX64.cmake ..
-      working-directory: ./build
-    - name: Build
-      run: ninja -C build
-    - uses: actions/upload-artifact@v2
-      with:
-        name: build
-        path: |
-          build/uking
-          data/uking_functions.csv

.github/workflows/check.yml

@@ -1,28 +0,0 @@
-name: check
-on:
-  workflow_run:
-    workflows: ["build"]
-    types:
-      - completed
-jobs:
-  check-matchings:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: haya14busa/action-workflow_run-status@967ed83efa565c257675ed70cfe5231f062ddd94
-    - uses: actions/checkout@v2
-    - run: git submodule update --init --recursive
-    - name: Install pip
-      run: sudo apt update && sudo apt install -y python3-pip python3-setuptools gpg wget
-    - name: Install tool dependencies
-      run: sudo python3 -m pip install capstone colorama cxxfilt pyelftools
-    - name: Download executable
-      run: wget https://static.zeldamods.org/botw/16A91992BBA71201E98756F3BC8F5D2F.elf.gpg
-    - name: Decrypt executable
-      run: gpg --quiet --batch --yes --decrypt --passphrase="${{ secrets.leo_secret }}" --output data/main.elf 16A91992BBA71201E98756F3BC8F5D2F.elf.gpg
-    - name: Download artifacts
-      uses: dawidd6/action-download-artifact@3cd20b2b63293848b29e22223f515baf725ed98f
-      with:
-        workflow: build.yml
-        name: build
-    - name: Check matchings
-      run: tools/check.py