Add Py3.13 Alpine container and CI build config (#10)

Install rust/cargo for Pendulum
to be removed, once Pendulum provides 3.13 wheels
https://github.com/sdispater/pendulum/issues/844

Based on Alpine, since Pendulum has Rust syntax
requiring an up-to-date Rust version, thing that
Debian 12 does not have (#11)

.gitlab-ci.yml

@@ -9,6 +9,7 @@ test_build_image:
     - docker build 3.10
     - docker build 3.11
     - docker build 3.12
+    - docker build 3.13
   except:
     - tags
 
@@ -47,3 +48,8 @@ build_3_12:
   extends: .build_image
   variables:
     PYTHON_VERSION: "3.12"
+
+build_3_13:
+  extends: .build_image
+  variables:
+    PYTHON_VERSION: "3.13"

3.13/Dockerfile

+FROM python:3.13-alpine
+
+# Install packages
+RUN apk add --no-cache libsodium-dev poetry cargo