… remove Graphene

feat: replace deprecated `starlette.graphql.GraphQLApp` with
`strawberry.fastapi.GraphQLRouter` and provide Strawberry schemas/mounts in:
- `tutorial2/usecase1.py`, `tutorial2/usecase2.py`
- `tutorial3/main.py`
- `tutorial4/main.py`
- `tutorial5/main.py`
- `tutorial6/main.py`
- `tutorial7/main.py`
- `tutorial8/main.py`
- `tutorial9/main.py`

feat: convert Graphene schema modules to Strawberry types:
- `tutorial3/schema.py` -> `Course`
- `tutorial4/schema.py` -> `Employee`
- `tutorial5/schema.py` -> `Weather`
- `tutorial8/schema.py` -> `Player` interface, `FootballPlayer`, `CricketPlayer`
- `tutorial9/schema.py` -> `FootballPlayer`, `CricketPlayer`, `Invalid`

feat: convert Graphene mapping modules to Strawberry `Query` implementations:
- `tutorial3/mapping.py`, `tutorial4/mapping.py`, `tutorial5/mapping.py`,
  `tutorial8/mapping.py`, `tutorial9/mapping.py`

fix: correct data and resolver bugs, remove minor issues and cleanup
- `tutorial2/usecase1.py`: fix typo `computer sience` → `computer science`; correct
  resolver parameter `into` → `info`.
- `tutorial2/usecase2.py`: remove redundant imports and avoid shadowing built-in
  `int`; convert to Strawberry types.
- `tutorial4/data.py`: use context manager (`with open`) and remove explicit `close()`.
- `tutorial5/data.py`, `tutorial9/data.py`: remove duplicated `data=data = [...]`.
- formatting/whitespace/trailing-newline cleanups across tutorials.

fix: remove all `import graphene` usages across the tutorial modules.

Notes:
- External packages `fastapi` and `strawberry` are required at runtime; static diagnostics
  may appear until dependencies are installed.
- Functionality preserved: resolvers now return typed Strawberry objects and routes are
  mounted at `/graphql` consistently.

… error, but import .data does not

…ant definitions in main

…r the data.csv file in tutorial4/data.csv where data.py could not find data.csv

…not through import errors duing app startup in uvicorn when running uvicorn from the root directory

…: Feat: replaced graphene with strawberry in tutorial modules