dockerimg: Fix development version detection when run with -C flag

When running sketch with the `-C` flag to change directories, the check for
development version should happen in the sketch directory, not the
target directory.

Co-Authored-By: sketch <hello@sketch.dev>
diff --git a/dockerimg/dockerimg.go b/dockerimg/dockerimg.go
index 0256798..3fb8b88 100644
--- a/dockerimg/dockerimg.go
+++ b/dockerimg/dockerimg.go
@@ -508,6 +508,21 @@
 }
 
 func buildLinuxSketchBin(ctx context.Context) (string, error) {
+	// Change to directory containing dockerimg.go for module detection
+	_, codeFile, _, _ := runtime.Caller(0)
+	codeDir := filepath.Dir(codeFile)
+	if currentDir, err := os.Getwd(); err != nil {
+		slog.WarnContext(ctx, "could not get current directory", "err", err)
+	} else {
+		if err := os.Chdir(codeDir); err != nil {
+			slog.WarnContext(ctx, "could not change to code directory for module check", "err", err)
+		} else {
+			defer func() {
+				_ = os.Chdir(currentDir)
+			}()
+		}
+	}
+
 	homeDir, err := os.UserHomeDir()
 	if err != nil {
 		return "", err