Upgrade step-runner to version 0.26.0

What does this MR do?

Upgrades the step-runner from version 0.24.0 to 0.26.0.

Step runner changes

v0.26.0

• Remove github.com/distribution/distribution/v3 dependencies from the step-runner go.mod. See 356.

v0.25.0

• Remove builtin step/oci/fetch and make it internal to the step-runner. See 354.
• Add OCI short reference parsing. See 355.

What are the relevant issue numbers?

• Dependency conflict: go.opentelemetry.io versio... (step-runner#348 - closed)
• Add short step reference for OCI image step (step-runner#179 - closed)