fix: typo in error handler for install-completion

[npdgm]

Fixes a Python typo in the error handler for oks-cli install-completion.
I'm running the CLI in a container and did not have the ps command, so the code was reached. Also confirmed by pylint -E.

[outscale-ykr]

Hi @npdgm

I tried to reproduce the problem with oks-cli install-completion inside a container. I used the following Dockerfile:

FROM python:3.12-slim

# Install git and certificates
RUN apt-get update && \
    apt-get install -y --no-install-recommends git ca-certificates && \
    rm -rf /var/lib/apt/lists/*

# Install oks-cli
RUN pip install --no-cache-dir git+https://github.com/npdgm/oks-cli.git

WORKDIR /app
ENTRYPOINT ["oks-cli"]

Then I built and ran the container:

docker build -t oks-cli .
docker run -it --rm oks-cli install-completion

Instead of the expected SubprocessError, I got a FileNotFoundError: [Errno 2] No such file or directory: 'ps'. So, I suggest updating the exception handling to include FileNotFoundError as well:

except (subprocess.SubprocessError, FileNotFoundError):