refactor: Update Dockerfile to install dependencies from requirements.txt

Dockerfile

@@ -6,7 +6,7 @@ WORKDIR /app
 COPY . .
 
 # Install dependencies
-RUN pip install grpcio google
+RUN pip install -r requirements.txt
 
 # Expose the port that greeter_server listens on
 EXPOSE 8080

requirements.txt

@@ -0,0 +1,5 @@
+coverage>=4.0
+cython>=3.0.0
+protobuf>=6.30.0,<7.0.0
+wheel>=0.29
+grpcio