Update build to poetry alpha 2 for python 3.10 (#1320)

* udpate build to poetry alpha 2 for python 3.10

* update testing workflow to run when workflow itself is changed

.github/workflows/testing.yaml

@@ -9,6 +9,7 @@ on:
     - 'tests/**'
     - 'poetry.lock'
     - 'pyproject.toml'
+    - '.github/workflows/testing.yaml'
   pull_request:
     branches: [ develop ]
     paths:
@@ -17,6 +18,7 @@ on:
     - 'tests/**'
     - 'poetry.lock'
     - 'pyproject.toml'
+    - '.github/workflows/testing.yaml'
 
 jobs:
   test:
@@ -64,7 +66,7 @@ jobs:
       if: ${{ matrix.python-version == '3.10-dev' }}
       run: |
         echo '::group::poetry'
-        pip install poetry==1.2.0a1
+        pip install poetry==1.2.0a2
         poetry config --local virtualenvs.in-project true
         echo '::endgroup::'