fix: replace the right Title from Stamps to Achievements

[furusin]

Issue

there is no issue about this PR. I just found a difference.

Overview (Required)

• replaced the right Title from Stamps to Achievements
  • Title
  • the title of bottomTab

Links

• Right design: https://www.figma.com/file/MbElhCEnjqnuodmvwabh9K/DroidKaigi-2023-App-UI?type=design&node-id=55510-31726&mode=design&t=mDOW4PL2sMMyJplu-4

Screenshot (Optional if screenshot test is present or unrelated to UI)

Before	After

[takahirom]

Thank you for your PR! But there is an issue for this and we have a pr. So let me close this.🙇 I'm looking forward to your next PR! https://github.com/DroidKaigi/conference-app-2023/pull/1063

[furusin]

thank you for your check!