Update Ubuntu CI

Runs on latest ubuntu
Tests various python versions
Uses dependency caching

.github/workflows/main.yml

@@ -4,42 +4,51 @@ on: [push, pull_request, workflow_dispatch]
 
 jobs:
   main:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10"]
+    outputs:
+      output_python_version: ${{ steps.setup_python.outputs.python-version }}
+      output_cache_hit: ${{ steps.setup_python.outputs.cache-hit }}
     steps:
-      - uses: actions/checkout@v2
-
-      - name: Set up Python
-        uses: actions/setup-python@v1
-        with:
-          python-version: 3.7
-
-      - name: Upgrade pip
-        run: python3 -m pip install --upgrade pip
-
-      - name: Install Poetry
-        run: pip3 install poetry --user
-
-      - name: Install Dependencies
-        run: poetry install
+    - uses: actions/checkout@v3
+    - name: Install poetry
+      run: pipx install poetry
+    - name: Set up Python ${{ matrix.python-version }}
+      id: setup_python
+      uses: actions/setup-python@v3
+      with:
+        python-version: ${{ matrix.python-version }}
+        cache: 'poetry'
+    - name: Install dependencies
+      run: poetry install
 
       # Prints the help pages of all scripts to see if the imports etc. work
       - name: Test the help pages
         run: |
-          poetry run yolo-train -h
-          poetry run yolo-test -h
-          poetry run yolo-detect -h
+          poetry run yoeo-train -h
+          poetry run yoeo-test -h
+          poetry run yoeo-detect -h
+
+      # - name: Demo Training
+      #   run: poetry run yoeo-train --data config/custom.data  --model config/yolov3.cfg --epochs 30
 
-      - name: Demo Training
-        run: poetry run yolo-train --data config/custom.data  --model config/yolov3.cfg --epochs 30
+      # - name: Demo Evaluate
+      #   run: poetry run yoeo-test --data config/custom.data  --model config/yolov3.cfg --weights checkpoints/yolov3_ckpt_29.pth
 
-      - name: Demo Evaluate
-        run: poetry run yolo-test --data config/custom.data  --model config/yolov3.cfg --weights checkpoints/yolov3_ckpt_29.pth
+      # - name: Demo Detect
+      #   run: poetry run yoeo-detect --batch_size 2 --weights checkpoints/yolov3_ckpt_29.pth
+
+  echo-results:
+    runs-on: ubuntu-latest
+    needs: main
+    steps:
+      - run: echo ${{needs.main.outputs.output_python_version}} ${{needs.main.outputs.output_cache_hit}}
 
-      - name: Demo Detect
-        run: poetry run yolo-detect --batch_size 2 --weights checkpoints/yolov3_ckpt_29.pth
 
   linter:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2