Fix non-zero exit from riot.

Makefile

@@ -5,7 +5,7 @@ RG=$(RG_ENV) relation-graph
 BG_RUNNER=JAVA_OPTS=-Xmx50G blazegraph-runner
 JVM_ARGS=JVM_ARGS=-Xmx120G
 ARQ=$(JVM_ARGS) arq
-BIOLINK=2.1.0
+BIOLINK=2.2.4
 
 all: ubergraph.jnl
 
@@ -63,9 +63,14 @@ opposites.ttl: antonyms_HP.txt
 
 # This includes a hack to workaround JSON-LD context problems with biolink
 # The conversion back to turtle works around a problem with Blazegraph parsing on Java 11
+# We need to filter out dateTime values because these are badly formatted in biolink and cause riot to have non-zero exit code
+# https://github.com/linkml/linkml/issues/253
 biolink-model.ttl:
 	curl -L 'https://raw.githubusercontent.com/biolink/biolink-model/$(BIOLINK)/biolink-model.ttl' -o $@.tmp
-	riot --syntax=turtle --output=ntriples $@.tmp | sed -E 's/<https:\/\/w3id.org\/biolink\/vocab\/([^[:space:]][^[:space:]]*):/<http:\/\/purl.obolibrary.org\/obo\/\1_/g' | riot --syntax=ntriples --output=turtle >$@
+	riot --syntax=turtle --output=ntriples $@.tmp |\
+	sed -E 's/<https:\/\/w3id.org\/biolink\/vocab\/([^[:space:]][^[:space:]]*):/<http:\/\/purl.obolibrary.org\/obo\/\1_/g' |\
+	grep -v 'http://www.w3.org/2001/XMLSchema#dateTime' |\
+	riot --syntax=ntriples --output=turtle >$@
 
 ubergraph.jnl: ontologies-merged.ttl subclass_closure.ttl is_defined_by.ttl properties-nonredundant.nt properties-redundant.nt opposites.ttl lexically-derived-opposites.nt lexically-derived-opposites-inverse.nt biolink-model.ttl
 	rm -f $@ &&\