grep fixed string

cdist/conf/type/__apt_mark/explorer/package_installed

@@ -25,6 +25,6 @@ else
 fi
 
 dpkg-query --show --showformat '${Status}' "$name" 2>/dev/null \
-    | grep -q 'ok installed' \
+    | grep -Fq 'ok installed' \
     && echo 0 \
     || echo 1

cdist/conf/type/__apt_mark/explorer/state

@@ -24,4 +24,4 @@ else
     name="$__object_id"
 fi
 
-apt-mark showhold | grep -q "$name" && echo hold || echo unhold
+apt-mark showhold | grep -Fq "$name" && echo hold || echo unhold