build-unit-test-docker: remove catch2

Based on searching the org in Github[1], there do not appear to be
anymore usages of Catch2.  Remove it from our Docker image.

1. https://github.com/search?q=org%3Aopenbmc+catch2&type=code

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I2cf89c533149266aa908a15bd825bfdbcd450c55
diff --git a/scripts/build-unit-test-docker b/scripts/build-unit-test-docker
index ddb4a45..b5b42c8 100755
--- a/scripts/build-unit-test-docker
+++ b/scripts/build-unit-test-docker
@@ -93,11 +93,6 @@
         build_type="custom",
         build_steps=[f"cp -a include/cereal/ {prefix}/include/"],
     ),
-    "catchorg/Catch2": PackageDef(
-        rev="v2.13.6",
-        build_type="cmake",
-        config_flags=["-DBUILD_TESTING=OFF", "-DCATCH_INSTALL_DOCS=OFF"],
-    ),
     "danmar/cppcheck": PackageDef(
         rev="27578e9c4c1f90c62b6938867735a054082e178e",
         build_type="cmake",