Implement Admin API (#512)

## Problem

Currently the Admin API is not supported in the python SDK.

## Solution

Implement an `Admin` class with support for CRUD on projects and API
keys.

## Usage

### Projects

```python
from pinecone import Admin

# Use service account credentials
admin = Admin(client_id='foo', client_secret='bar')

# Example: Create a project
project = admin.project.create(
    name="example-project",
    max_pods=5
)
print(f"Project {project.id} was created")

# Example: Rename a project
project = admin.project.get(name='example-project')
admin.project.update(
    project_id=project.id, 
    name='my-awesome-project'
)

# Example: Enable CMEK on all projects
project_list = admin.projects.list()
for proj in project_list_response.data:
    admin.projects.update(
      project_id=proj.id, 
      force_encryption_with_cmek=True
  )

# Example: Set pod quota to 0 for all projects
project_list = admin.projects.list()
for proj in project_list_response.data:
    admin.projects.update(project_id=proj.id, max_pods=0)

# Delete the project
admin.project.delete(project_id=project.id)

```

### API Keys

```python
from pinecone import Admin

# Use service account credentials
admin = Admin(client_id='foo', client_secret='bar')

project = admin.project.get(name='my-project')

# Create an API key
api_key_response = admin.api_keys.create(
    project_id=project.id,
    name="ci-key",
   roles=["ProjectEditor"]
)
key = api_key_response.value # 'pcsk_....'

# Look up info on a key by id
key_info = admin.api_keys.get(
    api_key_id=api_key_response.key.id
)

# Delete a key
admin.api_keys.delete(
    api_key_id=api_key_response.key.id
)
```


## Type of Change

- [x] New feature (non-breaking change which adds functionality)
- [x] Infrastructure change (CI configs, etc)
- [x] Non-code change (docs, etc)

## Test Plan

Tests added. Also incorporated into CI.

Author: jhamon

.github/actions/build-docs/action.yml

@@ -16,28 +16,7 @@ runs:
         include_asyncio: 'true'
         python_version: ${{ inputs.python-version }}
 
-    - name: Pretend this project requires Python 3.11
-      shell: bash
-      run: |
-        # Poetry won't let me install sphinx as a dev dependency in this project
-        # because of the wide range of versions our library supports. So during this
-        # action, we'll pretend this project requires Python 3.11 or greater.
-        sed -i 's/python = "^3.9"/python = "^3.11"/' pyproject.toml
-        poetry lock
-        poetry install -E grpc -E asyncio
-
-    - name: Install sphinx
-      shell: bash
-      run: |
-        poetry add sphinx myst-parser --group dev
-
     - name: Build html documentation
       shell: bash
       run: |
         poetry run sphinx-build -b html docs docsbuild
-
-    - name: Discard changes to pyproject.toml and poetry.lock
-      shell: bash
-      run: |
-        git checkout pyproject.toml
-        git checkout poetry.lock