Improve outdated tutorials check

[jooola]

• Extract summary building in a script that can be run locally
• Include the date of the tutorials in the summary table
• Add the year to the created issue title
• Test the workflow when files are changed in a pull_request

[jooola]

Allows the workflow to run on pull request, so we can test changes.

[jooola]

Only create an issue if the workflow is run from a schedule, since we only want to test the summary generation in pull requests.

[wpdevelopment11]

If you run outdated-tutorials-summary.sh on the first day of the month using cron:

community-content/.github/workflows/outdated-tutorials.yml

Lines 4 to 5 in 37f2d56

	schedule:
	- cron: "0 0 1 * *"

then tutorials written in the previous year, but not on the first day of the month will not be present in the table. You will need to wait two years to review them.

This condition will be false, because their timestamps will be bigger:

community-content/hack/outdated-tutorials-summary.sh

Line 43 in 37f2d56

if [[ "$last_year_timestamp" -ge "$date_timestamp" && "$last_year_month" == "$date_month" ]]; then

To reproduce, replace:

• last_year_timestamp=$(date +'%s' -d '1 year ago') with last_year_timestamp=$(date +'%s' -d '2023-12-01 00:00:00')
• last_year_month=$(date +'%m' -d '1 year ago') with last_year_month=12

This tutorial will not be present.