docs: the library version is modified to 0.1.8

[deyvidm18]

The version of the library is modified from 0.0.0 to 0.1.8 in the example using Maven

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

Fixes #<issue_number_goes_here> ☕️

[codecov]

Codecov Report

Merging #104 (dca7b65) into master (774e2ca) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #104   +/-   ##
=========================================
  Coverage     71.92%   71.92%           
  Complexity       55       55           
=========================================
  Files             6        6           
  Lines           342      342           
  Branches          4        4           
=========================================
  Hits            246      246           
  Misses           88       88           
  Partials          8        8           

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[Neenu1995]

Updating the README with latest version is an automated process and will overwrite this change.

[deyvidm18]

Hello @Neenu1995 but the automated process is not working. The readme shows 0.2.0 on maven version, for that reason my team stuck on a bug a couple of days.

com.google.cloud google-cloud-workflow-executions 0.2.0