fix: Use Spoon snapshot to fix incorrect indentation style

[slarse]

Fix #256

The latest snapshot build of Spoon works for resolving the problem with incorrect indentation. I suggest we simply use the snapshot build of Spoon (except for when we make a release), as I'm fairly often contributing to Spoon to fix issues in Sorald.

[codecov]

Codecov Report

Merging #272 (97da0a1) into master (37cecc0) will increase coverage by 0.44%.
The diff coverage is 95.00%.

@@             Coverage Diff              @@
##             master     #272      +/-   ##
============================================
+ Coverage     87.57%   88.01%   +0.44%     
- Complexity      447      485      +38     
============================================
  Files            47       52       +5     
  Lines          1521     1611      +90     
  Branches        208      213       +5     
============================================
+ Hits           1332     1418      +86     
- Misses          119      120       +1     
- Partials         70       73       +3     

Impacted Files	Coverage Δ	Complexity Δ
src/main/java/sorald/Constants.java	75.00% <ø> (ø)	1.00 <0.00> (ø)
src/main/java/sorald/Main.java	60.00% <0.00%> (-20.00%)	2.00 <0.00> (ø)
src/main/java/sorald/event/StatsMetadataKeys.java	0.00% <ø> (ø)	0.00 <0.00> (ø)
src/main/java/sorald/FileUtils.java	90.32% <66.66%> (-5.84%)	17.00 <3.00> (+3.00)	⬇️
src/main/java/sorald/cli/Cli.java	93.75% <92.30%> (-0.54%)	2.00 <1.00> (+1.00)	⬇️
...ald/event/collectors/MinerStatisticsCollector.java	96.00% <96.00%> (ø)	11.00 <11.00> (?)
src/main/java/sorald/event/EventType.java	100.00% <100.00%> (ø)	1.00 <0.00> (ø)
...c/main/java/sorald/event/models/ExecutionInfo.java	100.00% <100.00%> (ø)	5.00 <5.00> (?)
...main/java/sorald/event/models/WarningLocation.java	100.00% <100.00%> (ø)	7.00 <7.00> (?)
...main/java/sorald/event/models/miner/MinedRule.java	100.00% <100.00%> (ø)	4.00 <4.00> (?)
... and 7 more

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