Use v 32 of the web builder

The web builder is updated with a new debian version.
The tool we use in this repo to crate pdf from html : wkhtmltopdf
is no longer maintained and there is no straightforward way to
update it to work with newer debian.
Keep using this specific version as of now

.github/workflows/CI.yml

@@ -14,4 +14,4 @@ jobs:
   build:
     uses: bitcraze/workflows/.github/workflows/basic_build.yml@b59a297ee5a6105780d4ac832100f8990f243d04
     with:
-      builder_image: 'bitcraze/web-builder'
+      builder_image: 'bitcraze/web-builder:32'

.github/workflows/release.yml

@@ -9,5 +9,5 @@ jobs:
   build:
     uses: bitcraze/workflows/.github/workflows/basic_release.yml@b06a0f369e637f5f5a5f83f5e86d9b1f9e173289
     with:
-      builder_image: 'bitcraze/web-builder'
+      builder_image: 'bitcraze/web-builder:32'
       artifacts: 'generated/docs.zip generated/md.zip'