FTDCS-152 - Fix CircleCI configuration file

[JSRedondo]

Add the caret to the npm version to fix a common problem in the build.

[rowanmanning]

👍

[juanSanchezAlcala]

I had some troubles with that line too because it was detecting version 7 when it wasn't installed this happened with version 6.4.17 of npm or something similiar. The way that circleCi test this is with this lines

if npm -v | grep "$NPM_ORB_VERSION" > /dev/null 2>&1; then
echo "Success! NPM $(npm -v) has been installed to $(which npm)"
else
echo "Something went wrong; the specified version of NPM could not be installed"
exit 1
fi```
As you can se the grep is going to detect version 7 always when you have a this number inside the version.
So maybe with that line is not going to detect if you already have version 7 and always is going to try to install it . In my case i wrote in that line 7.24