fix: add albersdown to Suggests to resolve R CMD check NOTE

Vignettes use albersdown::theme_albers() but the package was not
declared in Suggests, causing an unstated dependency NOTE.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: bbuchsbaum

DESCRIPTION

@@ -49,7 +49,8 @@ Suggests:
     RNifti,
     future,
     future.apply,
-    pkgdown
+    pkgdown,
+    albersdown
 VignetteBuilder: knitr
 URL: https://github.com/bbuchsbaum/bidser, https://bbuchsbaum.github.io/bidser/
 BugReports: https://github.com/bbuchsbaum/bidser/issues