chore: release 5.2.0

[release-please]

🤖 I have created a release *beep* *boop*

5.2.0 (2020-06-30)

Features

• add code sample for creating an instance (#1073) (ab6dc62)
• secrets: begin migration to secret manager from keystore (#1092) (2031652)

Bug Fixes

• handle fallback option properly (#1146) (70d3f2c)
• samples-test: race condition in deleteData sample (#1156) (39d8f0c)
• race condition in "should transfer value from one record to another using DML statements within a transaction test" (#1159) (0c46714)
• set displayName in CreateInstance sample (#1145) (f9e47d9)
• set instanceId to the given id (#1094) (8973cbc), closes #1093
• unskip PDML tests when run against emulator (#1150) (8465482)
• update DELETE samples to match docs (#1072) (3336e04)
• update node issue template (#1157) (27d0699)

Performance Improvements

• use write fraction when resizing pool (#1031) (58f773b)

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This PR was generated with Release Please.

[codecov]

Codecov Report

Merging #1075 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master    #1075    +/-   ##
========================================
  Coverage   98.24%   98.24%            
========================================
  Files          23       23            
  Lines       20970    20970            
  Branches     1153     1034   -119     
========================================
  Hits        20601    20601            
  Misses        366      366            
  Partials        3        3            

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[yoshi-automation]

Release is at https://github.com/googleapis/nodejs-spanner/releases/tag/v5.2.0