Update Dockerfile for Python 3.10 and dependencies

[omaralvarez]

I tested the Dockerfile recently and it was not working with the current colmap image.

• Updated to Python 3.10 to avoid errors (This script does not work on Python 3.8. The minimum supported Python version is 3.10. Please use https://bootstrap.pypa.io/pip/3.8/get-pip.py instead.). Also for LoMa Add LoMa #495 it is needed.
• I have updated the MAINTAINER line because it is now deprecated and LABEL needs to be used.
• Combined apt update and get to save on layers.
• I added git to the dependencies since it was mising.
• Used an absolute path in the WORKDIR since it is good practice.

[Copilot]

Pull request overview

Updates the project Dockerfile to build successfully against the current colmap/colmap base image by moving to a newer Python version and adjusting a few Dockerfile best-practices.

Changes:

• Switch Python from 3.8 to 3.10 (via deadsnakes PPA) to restore get-pip.py compatibility and support newer components (e.g., LoMa work).
• Replace deprecated MAINTAINER with a LABEL and add git to apt dependencies.
• Use an absolute WORKDIR (/app) and combine apt-get update + apt-get install to reduce layers.

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[Copilot]

Consider adding --no-install-recommends and cleaning up apt metadata in the same RUN (e.g., removing /var/lib/apt/lists/* after install). Without this, the image retains apt cache data, increasing final image size and slowing pulls/builds.

Suggested change

	apt-get install -y git unzip wget software-properties-common
	RUN add-apt-repository ppa:deadsnakes/ppa && \
	apt-get -y update && \
	apt-get install -y python${PYTHON_VERSION}
	apt-get install -y --no-install-recommends git unzip wget software-properties-common && \
	rm -rf /var/lib/apt/lists/*
	RUN add-apt-repository ppa:deadsnakes/ppa && \
	apt-get -y update && \
	apt-get install -y --no-install-recommends python${PYTHON_VERSION} && \
	rm -rf /var/lib/apt/lists/*