0.26.0

Fixes

• Gemini: support combination of system message + empty user message + image (#269)

Other

• bump epam/ai-dial-ci from 2.4.0 to 2.4.1 (#270)
• bump fastapi from 0.115.2 to 0.116.1; bump starlette from 0.40.0 to 0.47.2 (#271)