add patern

src/app/signup/student-signup/student-signup.component.html

@@ -47,7 +47,7 @@
     
     <!-- Password -->
     <mat-form-field class="full-width">
-      <input matInput type="password" formControlName="password" placeholder="Mot de passe" required>
+      <input matInput type="password"  minlength="8" minlength="8" formControlName="password" placeholder="Mot de passe" pattern="(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$" required>
     </mat-form-field>
 
     <!-- Confirm password -->