CI: add Go 1.27 to CI

[cxlblm]

Summary

• Update LATEST_GO_VERSION from Go 1.26 to Go 1.27.
• Add Go 1.27 to the cross-platform test matrix.
• Remove TestHandlerName_differentFuncSameName, which depends on compiler-generated closure symbol names.

Background

Go 1.27 changed how function literals and closures are named by the compiler. A function literal now uses the same symbol name regardless of inlining, and multiple closure instances may share the same code and symbol name.

As a result, the following handlers:

h1 := handlerCreator("name1")
h2 := handlerCreator("name2")

previously had different names under older Go versions, but both resolve to the following name with Go 1.27:

github.com/labstack/echo/v5.TestHandlerName_differentFuncSameName.func1.func1

This behavior is documented in the Go 1.27 release notes. The reflect.Value.Pointer documentation also states that a function code pointer is not guaranteed to uniquely identify a function value.

Test removal

TestHandlerName_differentFuncSameName asserted exact compiler-generated names and required two closure instances to have different names. Neither behavior is guaranteed across Go versions, so the test has been removed.

This part may need further discussion. If retaining coverage for closure handlers is preferred, the test could instead verify only version-independent behavior, such as:

• HandlerName returns a non-empty value for a closure.
• Repeated calls for the same handler return a stable value.

It should not assert that separate closure instances have either equal or different names.

Verification

• go test ./... with Go 1.27.0
• All packages pass.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.71%. Comparing base (dcb05f0) to head (b8b1f3b).
⚠️ Report is 10 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3070      +/-   ##
==========================================
+ Coverage   93.34%   95.71%   +2.36%     
==========================================
  Files          43       44       +1     
  Lines        4735     4035     -700     
==========================================
- Hits         4420     3862     -558     
+ Misses        192      173      -19     
+ Partials      123        0     -123     

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[aldas]

LGTM