fix: open correct month for newsletter editing

Related to #18 (closed)

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feat(profile): add...
fix(annuaire): remove...

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How to set up and validate locally (or on alpha)

• yarn local-up
• Editer Newsletter.tsx line 37 pour mocker la date du jour ( les mois sont indexés de 0 à 11, exemple 31/05/2023 => Date(2023, 4, 31))
• Du 3 mai au 2 juin, on doit tomber sur la page de juin (qui est le bilan de mai)
• Du 3 juin au 2 juillet, on doit tomber sur la page de juillet (qui est le bilan de juin)
• etc...
• Pour le 3 décembre 2023 au 2 janvier 2024, on doit tomber sur la page de janvier 2024 (qui est le bilan de décembre 2023)

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• For the code that this change impacts, I believe that the automated tests validate functionality that is highly important to users. If the existing automated tests do not cover this functionality, I have added the necessary additional tests or I have added an issue to describe the automation testing gap and linked it to this MR.
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Related to #18 (closed)

src/components/Newsletter/Newsletter.tsx

@@ -30,14 +30,18 @@ export type ContentItems =
   | ''
 
 const Newsletter: React.FC = () => {
-  // Functional rule :
-  // Display next month after the 3rd of the current month
+  /**
+   * Display previous month until the newsletter is sent on the 3rd day of the month
+   */
   const getCurrentNewsletterDate = (): Date => {
-    const newsletterDate = new Date()
-    if (newsletterDate.getDate() >= 3) {
-      newsletterDate.setMonth(newsletterDate.getMonth() + 1)
-    }
-    return newsletterDate
+    const today = new Date()
+    const currentDay: number = today.getDate()
+    const currentMonth: number = today.getMonth()
+    const currentYear: number = today.getFullYear()
+
+    return currentDay < 3
+      ? new Date(currentYear, currentMonth, 1)
+      : new Date(currentYear, currentMonth + 1, 1)
   }
 
   const [date, setDate] = useState<Date>(getCurrentNewsletterDate())