Use Python 3.10 in Continuous Integration tests (#1577)

Updating the "GMT Dev Tests" GitHub Actions continuous integration
workflows that used Python 3.9 to use Python 3.10 now.

* Put quotes around 3.10 so that it doesn't get read as Python 3.1
* Manually install Python 3.10 on ci_tests_dev.yaml
* Use pip to install dvc on ci_tests_dev workflow

Workaround missing Python 3.10 packages for dvc
on conda-forge.

* Install numpy before other deps since it is a build dependency for some
* Prefer older binary pip packages over newer pip packages

Save from having to compile Python 3.10 packages,
and fixes installation issues for some libraries like
`aiohttp` which have outdated pre-release versions.

* Set minimum Python version to 3.8 in README.rst

Author: weiji14

.github/workflows/ci_docs.yml

@@ -25,7 +25,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.9]
+        python-version: ['3.9']
         os: [ubuntu-latest, macOS-latest, windows-latest]
         # Is it a draft Pull Request (true or false)?
         isDraft:

.github/workflows/ci_tests_dev.yaml

@@ -29,7 +29,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.9]
+        python-version: ['3.10']
         os: [ubuntu-latest, macOS-11.0, windows-2022]
         gmt_git_ref: [master]
     timeout-minutes: 30
@@ -77,7 +77,7 @@ jobs:
         uses: conda-incubator/[email protected]
         with:
           activate-environment: pygmt
-          python-version: ${{ matrix.python-version }}
+          # python-version: ${{ matrix.python-version }}
           channels: conda-forge,nodefaults
           channel-priority: strict
           miniforge-version: latest
@@ -88,11 +88,13 @@ jobs:
       # Install dependencies from conda-forge
       - name: Install dependencies
         run: |
-          mamba install ninja cmake libblas libcblas liblapack fftw gdal geopandas \
-                        ghostscript libnetcdf hdf5 zlib curl pcre make dvc
-          pip install --pre numpy pandas xarray netCDF4 packaging \
-                            ipython pytest-cov pytest-mpl pytest>=6.0 sphinx-gallery \
-                            tomli
+          mamba install python=${{ matrix.python-version }} \
+                        ninja cmake libblas libcblas liblapack fftw libgdal \
+                        geopandas ghostscript libnetcdf hdf5 zlib curl pcre make
+          pip install --pre --prefer-binary \
+                        numpy pandas xarray netCDF4 packaging \
+                        dvc ipython 'pytest>=6.0' pytest-cov \
+                        pytest-mpl sphinx-gallery tomli
 
       # Build and install latest GMT from GitHub
       - name: Install GMT ${{ matrix.gmt_git_ref }} branch (Linux/macOS)

README.rst

@@ -218,7 +218,7 @@ Compatibility with GMT/Python/NumPy versions
     * - `Dev <https://github.com/GenericMappingTools/pygmt/milestone/9>`_ (upcoming release)
       - `Dev Documentation <https://www.pygmt.org/dev>`_ (reflects `main branch <https://github.com/GenericMappingTools/pygmt>`_)
       - >=6.3.0
-      - >=3.7
+      - >=3.8
       - >=1.19
     * - `v0.5.0 <https://github.com/GenericMappingTools/pygmt/releases/tag/v0.5.0>`_ (latest release)
       - `v0.5.0 Documentation <https://www.pygmt.org/v0.5.0>`_