Merge ~jugmac00/launchpadlib:add-minimal-CI-configuration into launchpadlib:main

[Jürgen Gmach]

Add minimal CI configuration

[Andrey Fedoseev (andrey-fedoseev)]

> In order to run all tox environments, we need to discuss a proper way
how to provide different Python versions.

I guess, for that we can specify different test jobs for each series/python version:

jobs:
  test-focal:
    series: focal
    run: tox -e py38
  test-jammy:
    series: jammy
    run: tox -e py310

review: Approve

[Jürgen Gmach (jugmac00)]

Thanks for this idea, Andrey!

I think this is absolutely fine for most of our packages, but not perfect for `launchpadlib`, as this is a client library, which our users install, and we have no control over which Python version they would use, e.g. a friend of mine works for Red Hat and still uses `launchpadlib` and he runs Fedora with the whatever Python version he prefers.

[Andrey Fedoseev (andrey-fedoseev)]

Jürgen, with that approach we can test for all Python versions we are interested in, I suppose. I think we can find any Python version in either of Ubuntu series.

[Jürgen Gmach (jugmac00)]

Almost!

And indeed, when I think of Ubuntu, I wrongly only think of LTS releases:
https://jugmac00.github.io/blog/ubuntu-versions-cheat-sheet/

So, we could test all Python versions, except Python 3.11, as kinetic comes with Python 3.10, but this would mean that we need to spin up a new image for each Python version, and we could never just run `tox` or `tox -p` to cover all tests.

As mentioned, we will discuss this in Prague.

diff --git a/.launchpad.yaml b/.launchpad.yaml
 new file mode 100644
index 0000000..9f7ff95
--- /dev/null
+++ b/.launchpad.yaml
@@ -0,0 +1,19 @@
+pipeline:
+  - lint
+  - tests
+
+jobs:
+  lint:
+    architectures: amd64
+    packages:
+      - tox
+      - git
+    snaps: [go]
+    run: tox -e lint
+    series: focal
+  tests:
+    architectures: amd64
+    packages:
+      - tox
+    run: tox -e py38
+    series: focal
diff --git a/tox.ini b/tox.ini
index 62e0880..be0759a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,6 +9,14 @@ commands =
     coverage run -m pytest src/launchpadlib/tests {posargs}
 
 [testenv:lint]
+# necessary to build the woke linter
+setenv =
+    GOCACHE = {envdir}/gocache
+# adding http(s)_proxy is a workaround for
+# https://github.com/tox-dev/tox/pull/2378/files
+passenv =
+    http_proxy
+    https_proxy
 basepython =
     python3.8
 deps =