build(deps): bump ubuntu from 24.04 to 26.04

Bumps ubuntu from 24.04 to 26.04.

---
updated-dependencies:
- dependency-name: ubuntu
  dependency-version: '26.04'
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Dockerfile

@@ -1,5 +1,5 @@
 # Stage 1: Elfutils build stage
-FROM ubuntu:24.04 AS elfutils_builder
+FROM ubuntu:26.04 AS elfutils_builder
 ARG DEBIAN_FRONTEND=noninteractive
 ENV VERS=0.193
 
@@ -35,7 +35,7 @@ RUN apt-get update \
     && make install
 
 # Stage 2: Final stage
-FROM ubuntu:24.04
+FROM ubuntu:26.04
 ARG DEBIAN_FRONTEND=noninteractive
 LABEL org.opencontainers.image.source="https://github.com/bloomberg/pystack"