docs: update Alpine image for cilium/docs-builder

Update the version of the base image used for the docs-builder image.

A few packages have changed name and need to be updated. The path for
the workaround in the add-on for printing a warning banner on older
versions of the documentation also needs an update (alas, the related
issue humitos/sphinx-version-warning#22 is
still not solved).

Signed-off-by: Quentin Monnet <quentin@isovalent.com>

Documentation/Dockerfile

@@ -1,4 +1,4 @@
-FROM docker.io/library/python:3.7.9-alpine3.11
+FROM docker.io/library/python:3.10.4-alpine3.15
 
 LABEL maintainer="maintainer@cilium.io"
 
@@ -8,12 +8,13 @@ RUN apk add --no-cache --virtual --update \
     npm \
     bash \
     ca-certificates \
-    enchant \
+    enchant2 \
+    enchant2-dev \
     git \
     libc6-compat \
     py-pip \
-    python \
-    sphinx-python \
+    python3 \
+    py3-sphinx \
     gcc \
     musl-dev \
     && true
@@ -27,4 +28,4 @@ ENV READTHEDOCS_VERSION=$READTHEDOCS_VERSION
 ## Workaround odd behaviour of sphinx versionwarning extension. It wants to
 ## write runtime data inside a system directory.
 ## We do rely on this extension, so we cannot just drop it.
-RUN install -m 0777 -d /usr/local/lib/python3.7/site-packages/versionwarning/_static/data
+RUN install -m 0777 -d /usr/local/lib/python3.10/site-packages/versionwarning/_static/data

Documentation/requirements.txt

@@ -9,7 +9,7 @@ Jinja2==2.11.3
 jsonschema==2.6.0
 MarkupSafe==1.1.1
 myst-parser==0.17.0
-pyenchant==2.0.0
+pyenchant==3.2.2
 Pygments==2.7.4
 pytz==2018.7
 PyYAML==5.4