config: default to kgo dep version in ApiVersions

We can use debug.BuildInfo to determine which kgo version the user is
using.

We differ from sarama here by using the kgo version, rather than the
main module's version. This is more accurate to the client software name
/ version. Sarama uses the name "sarama", which will make it difficult
to match the version to the running program, since the version will be
for the binary, not the sarama library.

pkg/kgo/config.go

@@ -9,6 +9,7 @@ import (
 	"math/rand"
 	"net"
 	"regexp"
+	"runtime/debug"
 	"sync"
 	"time"
 
@@ -358,7 +359,24 @@ func (cfg *cfg) validate() error {
 	return nil
 }
 
-var defaultDialer = &net.Dialer{Timeout: 10 * time.Second}
+var (
+	defaultDialer = &net.Dialer{Timeout: 10 * time.Second}
+	reVersion     = regexp.MustCompile(`^[a-zA-Z0-9](?:[a-zA-Z0-9\.-]*[a-zA-Z0-9])?$`)
+)
+
+func softwareVersion() string {
+	info, ok := debug.ReadBuildInfo()
+	if ok {
+		for _, dep := range info.Deps {
+			if dep.Path == "github.com/twmb/franz-go" {
+				if reVersion.MatchString(dep.Version) {
+					return dep.Version
+				}
+			}
+		}
+	}
+	return "unknown"
+}
 
 func defaultCfg() cfg {
 	defaultID := "kgo"
@@ -375,7 +393,7 @@ func defaultCfg() cfg {
 		connIdleTimeout:        20 * time.Second,
 
 		softwareName:    "kgo",
-		softwareVersion: "0.1.0",
+		softwareVersion: softwareVersion(),
 
 		logger: new(nopLogger),
 
@@ -488,7 +506,7 @@ func ClientID(id string) Opt {
 // It is generally not recommended to set this. As well, if you do, the name
 // and version must match the following regular expression:
 //
-//     [a-zA-Z0-9](?:[a-zA-Z0-9\\-.]*[a-zA-Z0-9])?
+//     [a-zA-Z0-9](?:[a-zA-Z0-9\.-]*[a-zA-Z0-9])?
 //
 // Note this means neither the name nor version can be empty.
 func SoftwareNameAndVersion(name, version string) Opt {