Upgrade rules_pkg

The old rules result in this weird error that I can't figure out when
deploying the Julia runtime:

    $ sudo dpkg -i /tmp/frc971-scouting-julia_1_amd64.deb
    (Reading database ... 124346 files and directories currently installed.)
    Preparing to unpack .../frc971-scouting-julia_1_amd64.deb ...
    Unpacking frc971-scouting-julia (1) ...
    dpkg: error processing archive /tmp/frc971-scouting-julia_1_amd64.deb (--install):
     corrupted filesystem tarfile in package archive: unsupported PAX tar header type 'x'
    dpkg-deb: error: paste subprocess was killed by signal (Broken pipe)
    Errors were encountered while processing:
     /tmp/frc971-scouting-julia_1_amd64.deb

The new rules don't have this problem.

I also took this opportunity to drop a patch that we didn't need
anymore.

Signed-off-by: Philipp Schrader <philipp.schrader@gmail.com>
Change-Id: Iec2c0dcf27f76f83ab337da97a6caf0e182e706b
diff --git a/WORKSPACE b/WORKSPACE
index dd184d5..8a6206d 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -99,14 +99,10 @@
 
 http_archive(
     name = "rules_pkg",
-    patch_args = ["-p1"],
-    patches = [
-        "//third_party:rules_pkg/0001-Fix-tree-artifacts.patch",
-    ],
-    sha256 = "62eeb544ff1ef41d786e329e1536c1d541bb9bcad27ae984d57f18f314018e66",
+    sha256 = "8c20f74bca25d2d442b327ae26768c02cf3c99e93fad0381f32be9aab1967675",
     urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/rules_pkg/releases/download/0.6.0/rules_pkg-0.6.0.tar.gz",
-        "https://github.com/bazelbuild/rules_pkg/releases/download/0.6.0/rules_pkg-0.6.0.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_pkg/releases/download/0.8.1/rules_pkg-0.8.1.tar.gz",
+        "https://github.com/bazelbuild/rules_pkg/releases/download/0.8.1/rules_pkg-0.8.1.tar.gz",
     ],
 )
 
diff --git a/third_party/rules_pkg/0001-Fix-tree-artifacts.patch b/third_party/rules_pkg/0001-Fix-tree-artifacts.patch
deleted file mode 100644
index 567aba7..0000000
--- a/third_party/rules_pkg/0001-Fix-tree-artifacts.patch
+++ /dev/null
@@ -1,28 +0,0 @@
-From d654cc64ae71366ea82ac492106e9b2c8fa532d5 Mon Sep 17 00:00:00 2001
-From: Philipp Schrader <philipp.schrader@gmail.com>
-Date: Thu, 10 Mar 2022 23:25:21 -0800
-Subject: [PATCH] Fix tree artifacts
-
-For some reason the upstream code strips the directory names from the
-`babel()` rule that we use. This patch makes it so the directory is
-not stripped.  This makes runfiles layout in the tarball match the
-runfiles layout in `bazel-bin`.
----
- pkg/pkg.bzl | 4 ++--
- 1 file changed, 2 insertions(+), 2 deletions(-)
-
-diff --git a/pkg/pkg.bzl b/pkg/pkg.bzl
-index d7adbbc..a241b26 100644
---- a/pkg/pkg.bzl
-+++ b/pkg/pkg.bzl
-@@ -157,8 +157,8 @@ def _pkg_tar_impl(ctx):
-                     # Tree artifacts need a name, but the name is never really
-                     # the important part. The likely behavior people want is
-                     # just the content, so we strip the directory name.
--                    dest = "/".join(d_path.split("/")[0:-1])
--                    add_tree_artifact(content_map, dest, f, src.label)
-+                    #dest = "/".join(d_path.split("/")[0:-1])
-+                    add_tree_artifact(content_map, d_path, f, src.label)
-                 else:
-                     # Note: This extra remap is the bottleneck preventing this
-                     # large block from being a utility method as shown below.