Fix issue with access of _jacoco_runtime attribute now that it is no longer transitioned.

PiperOrigin-RevId: 949639038
Change-Id: I69a06ab82b9ef503873d5492ebdf89484b698853

rules/proguard.bzl

diff --git a/rules/proguard.bzl b/rules/proguard.bzl
index a1fdea7..2c55f9d 100644
--- a/rules/proguard.bzl
+++ b/rules/proguard.bzl
@@ -128,7 +128,7 @@
         proguard_specs_for_manifest = []):
     proguard_deps = utils.collect_providers(ProguardSpecInfo, utils.dedupe_split_attr(ctx.split_attr.deps))
     if ctx.configuration.coverage_enabled and hasattr(ctx.attr, "_jacoco_runtime"):
-        proguard_deps.append(utils.only(ctx.attr._jacoco_runtime)[ProguardSpecInfo])
+        proguard_deps.append(ctx.attr._jacoco_runtime[ProguardSpecInfo])
 
     local_proguard_specs = []
     if ctx.files.proguard_specs: