Bug: http://b/184876027

* remove unnecessary triggers.
 * explicitly specify branch for pull request trigger

* Port TFL kernel Gather to TFL Micro

* Remove TODO comment in micro/kernel/gather.cc
Co-authored-by: NAdvait Jain <advaitjain@users.noreply.github.com>

Bumps [tensorflow](https://github.com/tensorflow/tensorflow) from 2.4.0 to 2.5.0.
- [Release notes](https://github.com/tensorflow/tensorflow/releases)
- [Changelog](https://github.com/tensorflow/tensorflow/blob/master/RELEASE.md)
- [Commits](https://github.com/tensorflow/tensorflow/compare/v2.4.0...v2.5.0)
Signed-off-by: Ndependabot[bot] <support@github.com>
Co-authored-by: Ndependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

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

Co-authored-by: NAdvait Jain <advaitjain@users.noreply.github.com>

More context in http://b/188226023

Also, deleted some unused config from ci.yml

Co-authored-by: NAdvait Jain <advaitjain@users.noreply.github.com>

These visibility changes are specific to the TFLM code in
github.com/tensorflow/tflite-micro and would be awkward to upstream to
github.com/tensorflow/tensorflow.

Additionally, we are getting close to switching the current repository
to be the source of truth for TFLM code and have thus made the decision
to temporarily add some patches during the sync from upstream TF to the
current repo.

Manually tested that running `ci/sync_from_upstream_tf.sh` with the
current change avoids reverting the changes from #73 (such as with #76).

Progress towards http://b/187830287

keep @advaitjain as the sole codeowners for .github and ci

This change will allow me to test the sync workflow.

Co-authored-by: NAdvait Jain <advaitjain@users.noreply.github.com>

Co-authored-by: NAdvait Jain <advaitjain@users.noreply.github.com>

Since we trigger the CI workflow on any label change, when the cla:yes
label is applied the CI workflow will be run, and there is no way around
that with the current setup.

If the sync PR does not have the ci:run label, the checks will be
skipped but will still need to be run again prior to merge since
skipping the checks invalidates the previous completion of the required checks.

As a result, we are keeping the ci:run label. What this means is that
the reviewer can manually apply the cla:yes label and then start
auto-merge (which will wait for another round of the required checks to
be run).

Co-authored-by: NAdvait Jain <advaitjain@users.noreply.github.com>

cla:yes can only be applied by someone from Google, so will be done
manually. However, the goal here is to have the PR be ready to merge
once a Google engineer reviews it.

* Automatically remove the cla: no label and apply cla: yes label.
 * sync PR generation should not error out if there are no changes.

Co-authored-by: NAdvait Jain <advaitjain@users.noreply.github.com>