build-unit-test-docker: switch to ubuntu oracular

Ubuntu Oracular is released; switch to it.

As part of this, add systemd-dev to the dependencies in order to solve
the following build failure:
```
openbmc/phosphor-objmgr: Run-time dependency systemd found: NO (tried pkgconfig and cmake)
openbmc/phosphor-objmgr:
openbmc/phosphor-objmgr: meson.build:114:26: ERROR: Dependency "systemd" not found, tried pkgconfig and cmake
```

The systemd.pc file is only available as part of systemd-dev now.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I6fc4c67c0d5954f47e3752af9b335742901212ac
diff --git a/scripts/build-unit-test-docker b/scripts/build-unit-test-docker
index a1a9a64..79e75dd 100755
--- a/scripts/build-unit-test-docker
+++ b/scripts/build-unit-test-docker
@@ -700,7 +700,7 @@
 )
 force_build = os.environ.get("FORCE_DOCKER_BUILD")
 is_automated_ci_build = os.environ.get("BUILD_URL", False)
-distro = os.environ.get("DISTRO", "ubuntu:noble")
+distro = os.environ.get("DISTRO", "ubuntu:oracular")
 branch = os.environ.get("BRANCH", "master")
 ubuntu_mirror = os.environ.get("UBUNTU_MIRROR")
 docker_reg = os.environ.get("DOCKER_REG", "public.ecr.aws/ubuntu")
@@ -872,6 +872,7 @@
     software-properties-common \
     sudo \
     systemd \
+    systemd-dev \
     valgrind \
     vim \
     wget \