[llvm] Hashpin sensitive dependencies and configure dependabot to update them automatically (PR #75859)

[Aiden Grossman via llvm-commits]

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@@ -0,0 +1,18 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "monthly"
+    groups:
+      github-actions:
+        patterns:
+          - "*"
+  - package-ecosystem: "pip"
+    directory: "/llvm/docs"
+    schedule:
+      interval: "weekly"
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boomanaiden154 wrote:

Maybe change this to at least monthly too? Weekly I think would create a lot of unnecessary churn.

https://github.com/llvm/llvm-project/pull/75859