chore(dependabot): further refine Dependabot configuration

The current Dependabot configuration results in several breaking changes
to `package.json` and `pyproject.toml` files. Until we can get around
bringing all of our tooling up to date with their latest dependencies,
just ask Dependabot to limit its changes to minor updates in the
lockfiles.

Change-Id: I8a161c6373a24ae9b754eab47f04c3c3e85c449c
Signed-off-by: Chris Kay <chris.kay@arm.com>

.github/dependabot.yml

@@ -2,17 +2,19 @@ version: 2
 updates:
   - target-branch: "main"
     package-ecosystem: "npm"
-    directories: ["/"]
+    versioning-strategy: "lockfile-only"
+    directories: ["/", "/tools/conventional-changelog-tf-a"]
     schedule:
       interval: "daily"
     groups:
       dev-deps:
         patterns: ["*"]
-        update-types: ["major", "minor", "patch"]
+        update-types: ["minor", "patch"]
 
   - target-branch: "lts-v2.10"
     package-ecosystem: "npm"
-    directories: ["/"]
+    versioning-strategy: "lockfile-only"
+    directories: ["/", "/tools/conventional-changelog-tf-a"]
     schedule:
       interval: "daily"
     groups:
@@ -22,7 +24,8 @@ updates:
 
   - target-branch: "lts-v2.8"
     package-ecosystem: "npm"
-    directories: ["/"]
+    versioning-strategy: "lockfile-only"
+    directories: ["/", "/tools/conventional-changelog-tf-a"]
     schedule:
       interval: "daily"
     groups:
@@ -32,6 +35,7 @@ updates:
 
   - target-branch: "main"
     package-ecosystem: "pip"
+    versioning-strategy: "lockfile-only"
     directories: ["/", "/tools/cot_dt2c", "/tools/tlc"]
     schedule:
       interval: "daily"
@@ -42,6 +46,7 @@ updates:
 
   - target-branch: "lts-v2.10"
     package-ecosystem: "pip"
+    versioning-strategy: "lockfile-only"
     directories: ["/"]
     schedule:
       interval: "daily"
@@ -52,6 +57,7 @@ updates:
 
   - target-branch: "lts-v2.8"
     package-ecosystem: "pip"
+    versioning-strategy: "lockfile-only"
     directories: ["/"]
     schedule:
       interval: "daily"