[atomics.lockfree] "are" -> "is"; "along with" is not a coordinating

conjunction.

Author: zygoloid

source/atomics.tex

@@ -619,7 +619,7 @@
 At least one signed integral specialization of the \tcode{atomic} template,
 along with the specialization
 for the corresponding unsigned type\iref{basic.fundamental},
-are always lock-free.
+is always lock-free.
 \begin{note}
 This requirement is optional in freestanding implementations\iref{compliance}.
 \end{note}