feat(ci): add dependabot.yml groups (#533)

this commit introduces a collection of groups to our dependabot
configuration, to avoid excessive numbers of pull requests when families
of aggregate crates like `futures-*`, `tonic-*`, etc. release new
versions.

this follows the same convention as in other repositories such as e.g.
the proxy, which includes these groups as well.

Signed-off-by: katelyn martin <kate@buoyant.io>

Author: cratelyn

.github/dependabot.yml

@@ -4,6 +4,31 @@ updates:
     directory: /
     schedule:
       interval: daily
+    groups:
+      futures:
+        patterns:
+          - "futures*"
+      grpc:
+        patterns:
+          - "prost*"
+          - "tonic*"
+      hyper:
+        patterns:
+          - "hyper*"
+      pin-project:
+        patterns:
+          - "pin-project*"
+      rand:
+        patterns:
+          - "rand"
+          - "rand_*"
+      regex:
+        patterns:
+          - "regex"
+          - "regex-*"
+      tracing:
+        patterns:
+          - "tracing*"
 
   - package-ecosystem: gomod
     directory: /