Upgrading Python, adding --quality command, use uv instead of pipenv, change Dockerfile slightly, update README.md with changes

Dockerfile

@@ -1,8 +1,8 @@
-FROM python:3.13-slim-trixie
+FROM python:3.14-slim-trixie
 
 VOLUME /home
 
-COPY video_to_gif.py /home/video_to_gif.py
+COPY video_to_gif.py pyproject.toml uv.lock .python-version /home/
 
 WORKDIR /home
 
@@ -13,6 +13,10 @@ RUN apt update -y && \
     apt install curl -y && \
     apt install build-essential -y
 
+RUN pip install --upgrade pip && \
+    pip install uv && \
+    uv sync --frozen --no-dev
+
 # https://stackoverflow.com/a/49676568
 RUN curl https://sh.rustup.rs -sSf | bash -s -- -y
 ENV PATH="/root/.cargo/bin:${PATH}"
@@ -20,4 +24,4 @@ ENV PATH="/root/.cargo/bin:${PATH}"
 # https://crates.io/crates/gifski
 RUN cargo install gifski
 
-ENTRYPOINT ["python", "video_to_gif.py"]
+ENTRYPOINT ["uv", "run", "python", "video_to_gif.py"]