fix: change key to a unique element

Author: ShaileshS1702

lego-webapp/pages/lending/@lendableObjectId/LendingCalendar.tsx

@@ -320,27 +320,27 @@ const LendingCalendar = ({
                                 </Tooltip>
                               ))
                             ) : (
-                              <Tooltip
-                                key={idx}
+                                <Tooltip
+                                key={`${dateProps.day.format('YYYY-MM-DD')}-full`}
                                 className={styles.pin}
                                 content={
                                   fullLender ? (
-                                    <>
-                                      Lånt av:{' '}
-                                      <a
-                                        className={styles.lendingUserLink}
-                                        href={`/users/${userName}`}
-                                      >
-                                        <>{userDisplayName}</>
-                                      </a>
-                                    </>
+                                  <>
+                                    Lånt av:{' '}
+                                    <a
+                                    className={styles.lendingUserLink}
+                                    href={`/users/${userName}`}
+                                    >
+                                    <>{userDisplayName}</>
+                                    </a>
+                                  </>
                                   ) : (
-                                    <span>Lånt av: {userDisplayName}</span>
+                                  <span>Lånt av: {userDisplayName}</span>
                                   )
                                 }
-                              >
+                                >
                                 <div className={styles.timeRange} />
-                              </Tooltip>
+                                </Tooltip>
                             )}
                           </div>
                         </div>