dependabot: set pull-request limit to 5

Having the pull request limit set to 1 made dependabot to stay behind
on some dependencies updates. Hopefully, increasing the number of
parallel pull-requests that can be open will decrease the time a
dependency is not updated.

Signed-off-by: André Martins <andre@cilium.io>

.github/dependabot.yml

@@ -4,7 +4,7 @@ updates:
     directory: /
     schedule:
       interval: daily
-    open-pull-requests-limit: 1
+    open-pull-requests-limit: 5
     rebase-strategy: "disabled"
     ignore:
         # using a cilium-specific fork
@@ -20,7 +20,7 @@ updates:
     directory: /
     schedule:
       interval: daily
-    open-pull-requests-limit: 1
+    open-pull-requests-limit: 5
     rebase-strategy: "disabled"
     labels:
     - kind/enhancement
@@ -31,7 +31,7 @@ updates:
     schedule:
       interval: daily
     target-branch: "v1.10"
-    open-pull-requests-limit: 1
+    open-pull-requests-limit: 5
     rebase-strategy: "disabled"
     labels:
     - kind/enhancement
@@ -42,7 +42,7 @@ updates:
     schedule:
       interval: daily
     target-branch: "v1.9"
-    open-pull-requests-limit: 1
+    open-pull-requests-limit: 5
     rebase-strategy: "disabled"
     labels:
     - kind/enhancement
@@ -53,7 +53,7 @@ updates:
     schedule:
       interval: daily
     target-branch: "v1.8"
-    open-pull-requests-limit: 1
+    open-pull-requests-limit: 5
     rebase-strategy: "disabled"
     labels:
     - kind/enhancement