Precision issue in test_

[rlaboiss]

When the Debian package for praat is built on the supported architecture, there are building failures for some of them
(e.g. arm64). This is due to a failing assert in line 481 of file test_DataModeler.praat:

assert abs(.residualStdev - .residualStdevCertified) < 1e-14

Here are the results for each architecture:

architecture	.residualStdev	.residualStdev - .residualStdevCertified	result
amd64	0.8847963961443793	6.328271e-15	ok
arm64	0.8847963961443831	1.010303e-14	failure
armel	0.8847963961443857	1.265654e-14	failure
armhf	0.8847963961443857	1.265654e-14	failure
i386	0.8847963961443793	6.328271e-15	ok
mip64sel	0.8847963961443793	6.328271e-15	ok
ppc64el	0.8847963961443831	1.010303e-14	failure
riscv64	0.8847963961443831	1.010303e-14	failure

I have no idea why three different values are obtained in this set of architectures. At any rate, for now, I am increasing the tolerance to 1e-13 in the Debian package of praat, in order to have it included in the next release of the distribution.