Add GitHub Actions CI workflow for automated testing

[Copilot]

Added CI pipeline for the PyGMT nanobind benchmark implementation per maintainer request.

Workflow configuration (.github/workflows/test.yml):

• Test matrix: Python 3.11/3.12/3.13/3.14 on Ubuntu
• System deps: GMT library, Ghostscript, CMake, build-essential
• Package manager: uv for fast dependency resolution
• Test runner: pytest with verbose output and failure artifacts
• Code quality: ruff (format/lint) and mypy type checking in separate job

Triggers: Push to main/copilot branches, PRs to main

README update: Added CI status badge

Project configuration (pyproject.toml):

• Minimum Python version: 3.11
• Classifiers for Python 3.11, 3.12, 3.13, and 3.14
• Ruff and mypy target versions: Python 3.11

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[hironow]

@copilot plz add 3.13, 3.14 & drop 3.11

[Copilot]

Updated in commit 8409a38:

• Test matrix now includes Python 3.12, 3.13, and 3.14
• Removed Python 3.11
• Updated pyproject.toml to reflect new minimum version (>=3.12) and classifiers
• Updated ruff and mypy target versions to 3.12

[hironow]

@copilot plz check pr comments

[Copilot]

@copilot plz check pr comments

I've reviewed all PR comments. The only review comment (regarding Python versions) has been addressed in commit 8409a38. All changes are complete:

• ✅ Python 3.13 and 3.14 added to test matrix
• ✅ Python 3.11 removed
• ✅ pyproject.toml updated accordingly

No other actionable comments found.

[hironow]

@copilot plz revert "drop 3.11"

[Copilot]

@copilot plz revert "drop 3.11"

Reverted in commit 5f72f5b. Python 3.11 has been added back:

• Test matrix now includes: 3.11, 3.12, 3.13, and 3.14
• pyproject.toml updated to support >=3.11
• All tool configurations reverted to target Python 3.11