Fix code style and add copyright.

[pkufool]

@csukuangfj I disabled the E501 rule of flake8 for file egs/librispeech/ASR/conformer_ctc/conformer.py as it will cut the comments into annoying pieces, especially the example code.

[csukuangfj]

The following is how the CI checks the code style and format:

icefall/.github/workflows/style_check.yml

Lines 46 to 62 in 8469f9a

	- name: Install Python dependencies
	run: |
	python3 -m pip install --upgrade pip black flake8
	- name: Run flake8
	shell: bash
	working-directory: ${{github.workspace}}
	run: |
	# stop the build if there are Python syntax errors or undefined names
	flake8 . --count --show-source --statistics
	flake8 .
	- name: Run black
	shell: bash
	working-directory: ${{github.workspace}}
	run: |
	black --check --diff .

Could you fix the black version to the one mentioned in

icefall/.pre-commit-config.yaml

Lines 2 to 6 in 8469f9a

	- repo: https://github.com/psf/black
	rev: 21.6b0
	hooks:
	- id: black
	args: [--line-length=80]

i.e.

python3 -m pip install --upgrade pip black==21.6b0  flake8 

---

https://github.com/k2-fsa/icefall/blob/master/contributing.md
says how to set up the dev environment so that you can check the style locally.

[csukuangfj]

Did you reformat this file by hand or using black?

I just ran black on this file and nothing is changed.

(I am using black==21.6b0)

[pkufool]

I reverted the reformatting of conformer.py. It seems some conflicts between black and flake8, so ignored the E203 checking for that line.