Rewrite update.py to Python (#263)

Reasons were:

- one language make it easier for maintenance,
- workflow simplification,
- not stopping when a script fails anymore (it's better to have a partial update than nothing),
- use `GITHUB_OUTPUT` instead of the deprecated `set-output` command,
- display a workflow summary with statistics about scripts and information about updated products.

The commit message is not as good as it used to be, but it makes the diff process agnostic from the file format (will be needed soon when it will change), and it handles versions updates / removal, which was not supported by the previous script.

.github/dependabot.yml

@@ -1,6 +1,5 @@
 version: 2
 updates:
-
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
@@ -10,13 +9,3 @@ updates:
     directory: "/"
     schedule:
       interval: "monthly"
-
-  - package-ecosystem: "npm"
-    directory: "/"
-    schedule:
-      interval: "monthly"
-
-  - package-ecosystem: "bundler"
-    directory: "/"
-    schedule:
-      interval: "monthly"