make default installation faster (#2)

* remove cohere as default

* refractor dependencies

* use llama-index pdf reader as default (pypdf)

* fix some lazy docstring

* update install scripts

* minor fix

.github/workflows/unit-test.yaml

@@ -89,7 +89,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           cd libs/kotaemon
-          pip install -U --upgrade-strategy eager -e .[dev]
+          pip install -U --upgrade-strategy eager -e .[all]
 
       - name: New dependencies cache for key ${{ steps.restore-dependencies.outputs.cache-primary-key }}
         if: |