Arranged requirements of Context and Service

- Added missing requirement in Service
- Removed unneeded requirements.txt in Context

src/context/requirements.txt

-#
-# This file is autogenerated by pip-compile with python 3.9
-# To update, run:
-#
-#    pip-compile src/context/requirements.in
-#
-aniso8601==9.0.1
-    # via flask-restful
-attrs==21.2.0
-    # via pytest
-certifi==2021.5.30
-    # via requests
-charset-normalizer==2.0.6
-    # via requests
-click==8.0.1
-    # via flask
-flask==2.0.1
-    # via flask-restful
-flask-restful==0.3.9
-    # via -r src/context/requirements.in
-grpcio==1.41.0
-    # via
-    #   -r src/context/requirements.in
-    #   grpcio-health-checking
-grpcio-health-checking==1.41.0
-    # via -r src/context/requirements.in
-idna==3.2
-    # via requests
-iniconfig==1.1.1
-    # via pytest
-itsdangerous==2.0.1
-    # via flask
-jinja2==3.0.1
-    # via flask
-markupsafe==2.0.1
-    # via jinja2
-packaging==21.0
-    # via pytest
-pluggy==1.0.0
-    # via pytest
-prometheus-client==0.11.0
-    # via -r src/context/requirements.in
-protobuf==3.18.0
-    # via grpcio-health-checking
-py==1.10.0
-    # via pytest
-py-cpuinfo==8.0.0
-    # via pytest-benchmark
-pyparsing==2.4.7
-    # via packaging
-pytest==6.2.5
-    # via
-    #   -r src/context/requirements.in
-    #   pytest-benchmark
-pytest-benchmark==3.4.1
-    # via -r src/context/requirements.in
-pytz==2021.1
-    # via flask-restful
-redis==3.5.3
-    # via -r src/context/requirements.in
-requests==2.26.0
-    # via -r src/context/requirements.in
-six==1.16.0
-    # via
-    #   flask-restful
-    #   grpcio
-toml==0.10.2
-    # via pytest
-urllib3==1.26.7
-    # via requests
-werkzeug==2.0.1
-    # via flask

src/service/requirements.in

 anytree==2.8.0
 networkx==2.6.3
 pydot==1.4.2
+redis==4.1.2