refactor: drop logrus and other direct dependencies (#1319)

After https://gitea.com/gitea/runner/pulls/1304, logrus stayed only to forward logs from docker/cli and moby/go-archive. The runner used a small part of those: volume parsing, the build context tar, the `ssh://` connection and registry credentials. Own code that matches them replaces them, so logrus leaves the module graph. docker/cli stays for its logrus-free `opts` and `connhelper/ssh` packages.

Other dependencies that the standard library or existing ones cover go too: mergo, httprouter (replaced by `http.ServeMux`), retry-go, go-isatty, go-selinux, container-device-interface, gotest.tools and go-cmp (replaced by testify). The binary shrinks by 5%.

Behaviour differences:

1. An unreadable file in a build context is skipped with a warning, where go-archive left a truncated tar.
2. Build contexts no longer carry `security.capability` xattrs.
3. The cache and artifact servers answer HEAD on GET routes, and no longer redirect trailing slashes or answer OPTIONS.

*Written by Claude.*

---------

Co-authored-by: bircni <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1319
Reviewed-by: bircni <[email protected]>
Reviewed-by: Lunny Xiao <[email protected]>
Co-authored-by: silverwind <[email protected]>

act/common/logging/global.go

@@ -9,8 +9,6 @@ import (
 	"os"
 	"runtime"
 	"sync/atomic"
-
-	"github.com/sirupsen/logrus"
 )
 
 // TextOptions describes how the process-wide Logger writes a record as text.
@@ -41,11 +39,8 @@ func Default() *Logger { return std.Load() }
 // initial console Logger.
 func SetDefault(l *Logger) { std.Store(l) }
 
-// SetLevel sets the minimum level of the initial process-wide Logger and of what libraries log through logrus.
-func SetLevel(level Level) {
-	stdState.level.Set(slog.Level(level))
-	logrus.SetLevel(toLogrusLevel(level))
-}
+// SetLevel sets the minimum level of the initial process-wide Logger.
+func SetLevel(level Level) { stdState.level.Set(slog.Level(level)) }
 
 // GetLevel returns the minimum level of the initial process-wide Logger.
 func GetLevel() Level { return Level(stdState.level.Level()) }
@@ -72,7 +67,6 @@ func SetReportCaller(on bool) {
 	stdState.mu.Lock()
 	defer stdState.mu.Unlock()
 	stdState.reportCaller = on
-	logrus.SetReportCaller(on)
 }
 
 func Enabled(level Level) bool { return Default().Enabled(level) }