opentofu v0.1.0

Plugin opentofu Release v0.1.0 with changes since 14943c5

• Add configuration for OpenTofu (#22)
• ToolRegistry of Opentofu plugin (#23)
• Quicksync and Pipelinesync (#26)
• [OpenTofu Plugin] Plan stage (#28)
• add DetermineVersions method (#34)
• [OpenTofu Plugin] apply stage (#35)
• rollback stage (#37)
• change tds to rds (#38)
• Bump piped-plugin-sdk-go to v0.1.0 (#41)

example-stage v0.1.0

Plugin example-stage Release v0.1.0 with changes since 86482a3

• use the SDK in example-stage
• add tests in example
• Update example-stage README
• refine README template
• fix: add Makefile
• Fix Hello stage: Plan->Hello (#12)
• update SDK (#14)
• Bump sdk version for example-stage plugin (#42)

alpha: example-stage plugin

Linked to https://github.com/pipe-cd/pipecd/releases/tag/kubecon-jp-2025

See here for usage:
https://github.com/pipe-cd/pipecd/blob/master/cmd/pipedv1/README-usage-alpha.md