Update actions/upload-artifact requirement to 2.1.0 (#73)

Updates the requirements on [actions/upload-artifact](https://github.com/actions/upload-artifact) to permit the latest version.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/commits/ebad382c0953e8c6b4039e8d30dfd19ee7b2a862)

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/release-lce-utils.yml

@@ -34,7 +34,7 @@ jobs:
             delocate-wheel -w wheelhouse $f
           done
         shell: bash
-      - uses: actions/upload-artifact@v1
+      - uses: actions/upload-artifact@2.1.0
         with:
           name: ${{ runner.os }}-wheels
           path: wheelhouse
@@ -64,7 +64,7 @@ jobs:
           done
 
           ls -al wheelhouse/
-      - uses: actions/upload-artifact@v1
+      - uses: actions/upload-artifact@2.1.0
         with:
           name: ${{ runner.os }}-wheels
           path: wheelhouse
@@ -94,7 +94,7 @@ jobs:
           bazel-bin/larq_compute_engine/micro/tools/build_pip_pkg wheelhouse
 
         shell: bash
-      - uses: actions/upload-artifact@v1
+      - uses: actions/upload-artifact@2.1.0
         with:
           name: ${{ runner.os }}-wheels
           path: wheelhouse