feat(sdk)!: drop support for python 3.6 (kubeflow#7303)

* chore(sdk): drop support for python 3.6

* empty

* address comments

RELEASE.md

@@ -195,7 +195,7 @@ Note, when releasing from master, all the below mentions of "release branch" mea
     It will prompt you whether to push it to release branch. Press `y` and hit `Enter`.
 
     Note, the script will clone kubeflow/pipelines repo into a temporary location on your computer, make those changes and attempt to push to upstream, so that it won't interfere with your current git repo.
-    
+
     If you see error "docker.sock: connect: permission error", you need to [allow managing docker as a non-root user](https://docs.docker.com/engine/install/linux-postinstall/#manage-docker-as-a-non-root-user).
 
 1. View related cloudbuild jobs' statuses by clicking the latest commit's status icon
@@ -263,7 +263,7 @@ fill in the description. Detailed steps:
        <pre>
        To deploy Kubeflow Pipelines in an existing cluster, follow the instruction in [here](https://www.kubeflow.org/docs/pipelines/standalone-deployment-gcp/) or via UI [here](https://console.cloud.google.com/ai-platform/pipelines)
 
-       Install python SDK (python 3.6 above) by running:
+       Install python SDK (python 3.7 above) by running:
 
        ```bash
        python3 -m pip install kfp kfp-server-api --upgrade
@@ -309,7 +309,7 @@ Update master branch to the same version and include latest changelog:
     git commit -m "chore(release): bump version to $VERSION on master branch"
     ```
 
-1. If current release is not a prerelease, create a PR to update version in kubeflow documentation website: 
+1. If current release is not a prerelease, create a PR to update version in kubeflow documentation website:
 <https://github.com/kubeflow/website/blob/master/layouts/shortcodes/pipelines/latest-version.html>
 
    Note, there **MUST NOT** be a line ending in the file. Editing on GitHub always add a line ending
@@ -322,7 +322,7 @@ Update master branch to the same version and include latest changelog:
 
    and create a PR to update the version, e.g. <https://github.com/kubeflow/website/pull/1942>.
 
-1. Follow [Upgrade KFP](https://github.com/kubeflow/testing/tree/master/test-infra/kfp) instruction to upgrade KFP manifests in test-infra. 
+1. Follow [Upgrade KFP](https://github.com/kubeflow/testing/tree/master/test-infra/kfp) instruction to upgrade KFP manifests in test-infra.
 
 ## Release Process Development
 

sdk/python/requirements.in

@@ -35,5 +35,4 @@ absl-py>=0.9,<=0.11
 kfp-pipeline-spec>=0.1.14,<0.2.0
 fire>=0.3.1,<1
 pydantic>=1.8.2,<2
-dataclasses>=0.8,<1; python_version<"3.7"
-typing-extensions>=3.7.4,<5; python_version<"3.9"
+typing-extensions>=3.7.4,<4; python_version<"3.9"

sdk/python/setup.py

@@ -57,8 +57,7 @@
     'pydantic>=1.8.2,<2',
     'typer>=0.3.2,<1.0',
     # Standard library backports
-    'dataclasses;python_version<"3.7"',
-    'typing-extensions>=3.7.4,<5;python_version<"3.9"',
+    'typing-extensions>=3.7.4,<4;python_version<"3.9"',
 ]
 
 EXTRAS_REQUIRE = {
@@ -131,7 +130,6 @@ def read_readme():
         'Intended Audience :: Science/Research',
         'License :: OSI Approved :: Apache Software License',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',
@@ -141,7 +139,7 @@ def read_readme():
         'Topic :: Software Development :: Libraries',
         'Topic :: Software Development :: Libraries :: Python Modules',
     ],
-    python_requires='>=3.6.1',
+    python_requires='>=3.7.0',
     include_package_data=True,
     entry_points={
         'console_scripts': [