Add checksums for ES 7.5.2 to attributes

[dwilches]

Hello, Could you add the checksums for version 7.5.2 to attributes/default.rb? Thanks.

The checksums in this PR were generated as:

$ wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.5.2-x86_64.rpm
$ wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.5.2-linux-x86_64.tar.gz
$ wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.5.2-amd64.deb
$ sha256sum elasticsearch-7.5.2-amd64.deb elasticsearch-7.5.2-linux-x86_64.tar.gz elasticsearch-7.5.2-x86_64.rpm
4d5d2aa01a29bab054dd67a7c39d330d5c3844aa686846a8bd9ddf841834f485  elasticsearch-7.5.2-amd64.deb
7b49b5ad9fea43533fc0355708b0fad7651aa0215fd590ed1414c2ff44e4cdf3  elasticsearch-7.5.2-linux-x86_64.tar.gz
bf34b74295be1768e456d4c9b5431d6e4caac64afb92afef686fa4228e4a5c57  elasticsearch-7.5.2-x86_64.rpm

[damacus]

Resolving via #767