ci: more usable separator (#9890)

### Description

The `/`s in the branch names make it a little annoying to run
`create-turbo` on the branches for the Dependabot upgrades. It's easy to
forget to have to use `create-turbo --example-path` rather than just
`--example`.

Using `-` for separators is just a slight bit simpler.

Author: anthonyshew

.github/dependabot.yml

@@ -11,6 +11,8 @@ updates:
     labels:
       - "area: examples"
     open-pull-requests-limit: 1
+    pull-request-branch-name:
+      separator: "-"
     versioning-strategy: "increase"
     allow:
       - dependency-type: "direct"
@@ -30,6 +32,8 @@ updates:
     labels:
       - "area: examples"
     open-pull-requests-limit: 1
+    pull-request-branch-name:
+      separator: "-"
     versioning-strategy: "increase"
     allow:
       - dependency-type: "direct"
@@ -59,6 +63,8 @@ updates:
     labels:
       - "area: examples"
     open-pull-requests-limit: 1
+    pull-request-branch-name:
+      separator: "-"
     versioning-strategy: "increase"
     allow:
       - dependency-type: "direct"
@@ -78,6 +84,8 @@ updates:
     labels:
       - "area: examples"
     open-pull-requests-limit: 1
+    pull-request-branch-name:
+      separator: "-"
     versioning-strategy: "increase"
     allow:
       - dependency-type: "direct"
@@ -97,6 +105,8 @@ updates:
     labels:
       - "area: examples"
     open-pull-requests-limit: 1
+    pull-request-branch-name:
+      separator: "-"
     versioning-strategy: "increase"
     allow:
       - dependency-type: "direct"
@@ -116,6 +126,8 @@ updates:
     labels:
       - "area: examples"
     open-pull-requests-limit: 1
+    pull-request-branch-name:
+      separator: "-"
     versioning-strategy: "increase"
     allow:
       - dependency-type: "direct"