chore: use poetry as dependency manager (#242)

* Adopts [Poetry](https://python-poetry.org/) as a dependency manager
* Introduces dependency version requirements
* Deprecates Python 3.7 support

**TODO**
- [x] Update developer guide
- [x] Add back `playwright`, `manifest-ml`, and `jupyter` to dependency
group

**Not Doing => Fast Follow**
- Investigate single source for version, perhaps relying on GitHub tags
and [tackling this
issue](https://github.com/hwchase17/langchain/issues/26)

.github/workflows/lint.yml

@@ -1,23 +1,35 @@
 name: lint
 
-on: [push, pull_request]
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+env:
+  POETRY_VERSION: "1.2.0"
 
 jobs:
   build:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.7"]
+        python-version: 
+         - "3.8"
+         - "3.9"
+         - "3.10"
     steps:
     - uses: actions/checkout@v3
+    - name: Install poetry
+      run: |
+        pipx install poetry==$POETRY_VERSION
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
+        cache: poetry
     - name: Install dependencies
       run: |
-        python -m pip install --upgrade pip
-        pip install -r test_requirements.txt
+        poetry install
     - name: Analysing the code with our lint
       run: |
         make lint

.github/workflows/test.yml

@@ -1,23 +1,33 @@
 name: test
 
-on: [push, pull_request]
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+env:
+  POETRY_VERSION: "1.2.0"
 
 jobs:
   build:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.7"]
+        python-version:
+         - "3.8"
+         - "3.9"
+         - "3.10"
     steps:
     - uses: actions/checkout@v3
+    - name: Install poetry
+      run: pipx install poetry==$POETRY_VERSION
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
+        cache: 'poetry'
     - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip
-        pip install -r test_requirements.txt
+      run: poetry install
     - name: Run unit tests
       run: |
         make tests