Go Toolchain issues

As flagged in https://github.com/deepmap/oapi-codegen/issues/1221, folks using Go 1.21 for their local builds - but maybe not targeting Go 1.21, will have been receiving diffs like:

 diff --git a/examples/go.mod b/examples/go.mod
index 4b815bd..929a5b6 100644
--- a/examples/go.mod
+++ b/examples/go.mod
@@ -1,6 +1,8 @@
 module github.com/deepmap/oapi-codegen/examples
 
-go 1.20
+go 1.21
+
+toolchain go1.21.0

This is due to changes in Go 1.21's management of toolchains, and is a side effect of Fiber and Iris targeting Go 1.21.

These dependencies have now been downgraded to requiring 1.20, and we've taken steps as maintainers to reduce the impact in the future, so we should only be targeting the lowest Go version supported by the Go team.

What's Changed

• [Gorilla] update the MiddlewareFunc type for compatibility by @namco1992 in https://github.com/deepmap/oapi-codegen/pull/1134
• Re-enable moq's execution by @jamietanna in https://github.com/deepmap/oapi-codegen/pull/1229
• Bump fiber to v2.49.1 by @jamietanna in https://github.com/deepmap/oapi-codegen/pull/1232
• Build project with Go 1.20 and Go 1.21 by @jamietanna in https://github.com/deepmap/oapi-codegen/pull/1251
• Bump Iris to remove Go 1.21 dependency by @jamietanna in https://github.com/deepmap/oapi-codegen/pull/1249

New Contributors

• @namco1992 made their first contribution in https://github.com/deepmap/oapi-codegen/pull/1134

Full Changelog: https://github.com/deepmap/oapi-codegen/compare/v1.14.0...v1.15.0