[EN-8798][PythonAPI] Lock the Сython version# Please enter the commit…

… message for your changes. Lines starting

.github/workflows/test_on_pr.yml

@@ -29,9 +29,8 @@ jobs:
     - name: Set poetry env
       run: |
         pip install --upgrade pip
-        pip install taskipy cython toml
-        poetry install --only main
-        task build -f sdist
+        poetry install
+        poetry run task build_inplace
         pip uninstall --yes taskipy cython
       shell: bash
 
@@ -65,7 +64,6 @@ jobs:
     - name: Set poetry env
       run: |
         pip install --upgrade pip
-        pip install taskipy cython toml
         poetry install
       shell: bash