ci: Move micro_http to rust-vmm dependabot group

This crate depends upon vmm-sys-util which is in this group so it also
needs to be in that group.

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>

Author: rbradford

.github/dependabot.yml

@@ -11,6 +11,7 @@ updates:
     - dependency-name: "kvm-bindings"
     - dependency-name: "kvm-ioctls"
     - dependency-name: "linux-loader"
+    - dependency-name: "micro_http"
     - dependency-name: "mshv-bindings"
     - dependency-name: "mshv-ioctls"
     - dependency-name: "seccompiler"
@@ -41,6 +42,7 @@ updates:
     - dependency-name: "kvm-bindings"
     - dependency-name: "kvm-ioctls"
     - dependency-name: "linux-loader"
+    - dependency-name: "micro_http"
     - dependency-name: "mshv-bindings"
     - dependency-name: "mshv-ioctls"
     - dependency-name: "seccompiler"