Decrease the package size

[barjin]

Recent updates bumped the apify-client uncompressed package size to >7 MB. Since this package is used in web applications, this can cause longer loading times in downstream web projects (and longer installs in Node.JS projects).

VERSION            SIZE (KB)
-------            ---------
2.19.1-beta.8         2375.2
2.19.1-beta.9         2378.9
2.19.1-beta.10        2380.0
2.20.0                2380.3
2.20.1-beta.0         2380.0
2.20.1-beta.1         2379.9
2.20.1-beta.2         2379.9
2.20.1-beta.3         7267.1
2.20.1-beta.4         7301.4
2.20.1-beta.5         7280.2
2.20.1-beta.6         7280.4
2.20.1-beta.7         7280.4
2.20.1-beta.8         7588.7
2.20.1-beta.9         7588.7
2.20.1-beta.10        7609.7
2.20.1-beta.11        7607.4
2.20.1-beta.12        7607.7
2.20.1-beta.13        7607.7
2.21.0                7608.1
2.21.1-beta.0         7607.7

A quick look at the data points at #791 (2.20.1-beta.3) increasing the bundle size the most.