chore: add clirr-ignored-differences.xml for new runAsyncTransaction methods added to Firestore

[BenWhitehead]

Fixes the broken build from new methods added in #103

[codecov]

Codecov Report

Merging #143 into master will increase coverage by 0.05%.
The diff coverage is 95.23%.

@@             Coverage Diff              @@
##             master     #143      +/-   ##
============================================
+ Coverage     71.56%   71.62%   +0.05%     
- Complexity      968      969       +1     
============================================
  Files            62       62              
  Lines          5202     5222      +20     
  Branches        579      579              
============================================
+ Hits           3723     3740      +17     
- Misses         1299     1302       +3     
  Partials        180      180              

Impacted Files	Coverage Δ	Complexity Δ
...n/java/com/google/cloud/firestore/Transaction.java	97.77% <ø> (ø)	11.00 <0.00> (ø)
...java/com/google/cloud/firestore/FirestoreImpl.java	82.35% <95.23%> (+0.28%)	24.00 <1.00> (+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 d3458cb...cfe23ad. Read the comment docs.