feat: add ARM64/AArch64 build support to Dockerfile-base (#3346)

* Add support for capability to build arm64 image

* Fixing wrong variable TARGETPLATFORM bug

* Adding missing semicolons

* skip docker hub login if PR (no push) or no credentials

* Enabling arm64 builds for Dockerfile-base in Github actions

* TARGETARCH automatically default to platform arch under build

* Enabling arm64 builds for axolotl docker builds

* Enabling arm64 builds for axolotl-cloud docker build Github actions

---------

Co-authored-by: Wing Lian <wing@axolotl.ai>

.github/workflows/base.yml

@@ -79,6 +79,7 @@ jobs:
             axolotlai/axolotl-base
       - name: Login to Docker Hub
         uses: docker/login-action@v2
+        if: ${{ github.event_name != 'pull_request' && secrets.DOCKERHUB_USERNAME != '' && secrets.DOCKERHUB_TOKEN != '' }}
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
@@ -89,6 +90,7 @@ jobs:
         with:
           context: .
           file: ./docker/${{ matrix.dockerfile }}
+          platforms: linux/amd64,linux/arm64
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.metadata.outputs.tags }}-base-py${{ matrix.python_version }}-cu${{ matrix.cuda }}-${{ matrix.pytorch }}${{ matrix.axolotl_extras != '' && '-' || '' }}${{ matrix.axolotl_extras }}
           labels: ${{ steps.metadata.outputs.labels }}