chore(deps): update dependency com.google.cloud:libraries-bom to v20.2.0

[renovate-bot]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
com.google.cloud:libraries-bom	20.1.0 -> 20.2.0

---

Configuration

📅 Schedule: At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻️ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box.

---

This PR has been generated by WhiteSource Renovate. View repository job log here.

[codecov]

Codecov Report

Merging #1111 (0edb3cd) into master (37ca990) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #1111      +/-   ##
============================================
- Coverage     84.99%   84.95%   -0.05%     
+ Complexity     2727     2723       -4     
============================================
  Files           156      156              
  Lines         14410    14410              
  Branches       1379     1379              
============================================
- Hits          12248    12242       -6     
- Misses         1593     1598       +5     
- Partials        569      570       +1     

Impacted Files	Coverage Δ	Complexity Δ
.../google/cloud/spanner/AbstractLazyInitializer.java	92.85% <0.00%> (-7.15%)	4.00% <0.00%> (-1.00%)
...ud/spanner/SessionPoolAsyncTransactionManager.java	85.03% <0.00%> (-1.58%)	13.00% <0.00%> (-2.00%)
...m/google/cloud/spanner/connection/SpannerPool.java	87.16% <0.00%> (-0.54%)	33.00% <0.00%> (ø%)
...ain/java/com/google/cloud/spanner/SessionPool.java	88.82% <0.00%> (-0.20%)	74.00% <0.00%> (ø%)
...a/com/google/cloud/spanner/SessionPoolOptions.java	69.53% <0.00%> (ø)	17.00% <0.00%> (-1.00%)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 37ca990...0edb3cd. Read the comment docs.