Fix typo in `library/entropy.c`

Signed-off-by: Zachary Fleckenstein <ZachFleck42@Gmail.com>
diff --git a/library/entropy.c b/library/entropy.c
index e3b337f..77e2bfd 100644
--- a/library/entropy.c
+++ b/library/entropy.c
@@ -590,7 +590,7 @@
 }
 
 /*
- * A test to ensure hat the entropy sources are functioning correctly
+ * A test to ensure that the entropy sources are functioning correctly
  * and there is no obvious failure. The test performs the following checks:
  *  - The entropy source is not providing only 0s (all bits unset) or 1s (all
  *    bits set).