chore(ci): remove Travis CI (#309)

We've been out of credits for 8 months with no builds triggered on Travis CI.

This leaves PR untested for alternative architectures (well, they've been untested for 8 months already).
We can just rely on GHA scheduled builds for those architectures.
Tags are also built using GHA for those architectures.

CONTRIBUTING.rst

@@ -102,9 +102,8 @@ Before you submit a pull request, check that it meets these guidelines:
    your new functionality into a function with a docstring, and add the
    feature to the list in `README.rst`.
 
-3. The pull request should work for Python 2.7, and 3.5+.
+3. The pull request should work for Python 2.7, and 3.6+.
    Check `GitHub Actions https://github.com/scikit-build/cmake-python-distributions/actions/workflows/build.yml`_
-   and `TravisCi <https://travis-ci.org/scikit-build/cmake-python-distributions/pull_requests>`_
    and make sure that the tests pass for all supported Python versions.
 
 

README.rst

@@ -30,12 +30,12 @@ Build Status
 
 .. table::
 
-  +---------------+--------------------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------+
-  |               | GitHub Actions (Windows, macOS, Linux)                                                                       | Travis CI (alternative archs)                                                               |
-  +===============+==============================================================================================================+=============================================================================================+
-  | PyPI          | .. image:: https://github.com/scikit-build/cmake-python-distributions/actions/workflows/build.yml/badge.svg  | .. image:: https://travis-ci.com/scikit-build/cmake-python-distributions.svg?branch=master  |
-  |               |     :target: https://github.com/scikit-build/cmake-python-distributions/actions/workflows/build.yml          |     :target: https://travis-ci.com/github/scikit-build/cmake-python-distributions           |
-  +---------------+--------------------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------+
+  +---------------+--------------------------------------------------------------------------------------------------------------+
+  |               | GitHub Actions (Windows, macOS, Linux)                                                                       |
+  +===============+==============================================================================================================+
+  | PyPI          | .. image:: https://github.com/scikit-build/cmake-python-distributions/actions/workflows/build.yml/badge.svg  |
+  |               |     :target: https://github.com/scikit-build/cmake-python-distributions/actions/workflows/build.yml          |
+  +---------------+--------------------------------------------------------------------------------------------------------------+
 
 Platforms
 ---------

docs/make_a_release.rst

@@ -13,7 +13,7 @@ This is usually done after :ref:`updating_cmake_version`.
 Prerequisites
 -------------
 
-* All CI tests are passing on `GitHub Actions`_ and `Travis CI`_ (if credits are available).
+* All CI tests are passing on `GitHub Actions`_.
 
 * You have a `GPG signing key <https://help.github.com/articles/generating-a-new-gpg-key/>`_.
 
@@ -36,7 +36,7 @@ means that ``echo "Hello"`` should be copied and evaluated in the terminal.
 `PyPI`_: Step-by-step
 ---------------------
 
-1. Make sure that all CI tests are passing on `GitHub Actions`_ and `Travis CI`_ (if credits are available).
+1. Make sure that all CI tests are passing on `GitHub Actions`_.
 
 
 2. Download the latest sources
@@ -127,6 +127,5 @@ means that ``echo "Hello"`` should be copied and evaluated in the terminal.
 
 
 .. _GitHub Actions: https://github.com/scikit-build/cmake-python-distributions/actions/workflows/build.yml
-.. _Travis CI: https://travis-ci.org/scikit-build/cmake-python-distributions/pull_requests
 
 .. _PyPI: https://pypi.org/project/cmake