Change shebang to "#!/usr/bin/env python3" in python shell scripts. Fix #103

.gitlab-ci-docker.yaml

hive/cli.py

hive/utils/profiler.py

scripts/ci/benchmark_generator.py

scripts/ci/json_report_parser.py

scripts/ci/start_api_benchmark.py

scripts/operation_extractor.py

scripts/xml_report_parser.py

.../manual_tests/list_comments_by_author_last_update_test.py

tests/manual_tests/list_comments_by_cashout_test.py

tests/manual_tests/list_comments_by_parent_test.py

tests/manual_tests/list_comments_by_permlink.py

tests/manual_tests/list_comments_by_root_test.py

tests/manual_tests/list_comments_by_update_test.py