Remove srtpfilter_unittest rule from DEPS

srtpfilter was a SDES thing which is gone.

BUG=None

Change-Id: I060582b5ba9e72d1fdad3662e2b478042f0c780c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/370640
Commit-Queue: Philipp Hancke <phancke@meta.com>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43517}

pc/DEPS

@@ -16,9 +16,3 @@ include_rules = [
   "+system_wrappers",
   "+absl/strings/str_cat.h",
 ]
-
-specific_include_rules = {
-  "srtpfilter_unittest\.cc": [
-    "+crypto",
-  ],
-}