[fix] tagName="div" multiline="p" --> tagName="p"

As per documentation here, ` multiline="p"` has been deprecated. We should change the RichText into InnerBlock:
- WordPress/gutenberg#59318
- https://dlxplugins.com/tutorials/say-goodbye-to-richtext-multiline-how-to-use-innerblocks-instead/
- https://github.com/DLXPlugins/DLXRichText/blob/innerblocks/src/blocks/dlxrichtext/edit.js

src/epfl-contact/index.js

@@ -145,26 +145,23 @@ registerBlockType( 'epfl/contact', {
                     <label><strong>Information</strong></label>
                     <hr />
                     <RichText
-                        tagName="div"
-                        multiline="p"
+                        tagName="p"
                         placeholder={ __( 'An email ?', 'epfl' ) }
                         value={ attributes.information1 }
                         className="information1"
                         onChange={ information1 => setAttributes( { information1 } ) }
                     />
                     <hr />
                     <RichText
-                        tagName="div"
-                        multiline="p"
+                        tagName="p"
                         placeholder={ __( 'A phone number ?', 'epfl' ) }
                         value={ attributes.information2 }
                         className="information2"
                         onChange={ information2 => setAttributes( { information2 } ) }
                     />
                     <hr />
                     <RichText
-                        tagName="div"
-                        multiline="p"
+                        tagName="p"
                         placeholder={ __( 'An address ?', 'epfl' ) }
                         value={ attributes.information3 }
                         className="information3"