fix: build.gradle downgrade to 2.13.5

[CAMOBAP]

Jackson 2.14 will require Android SDK 26 so downgrading back to 2.13.x

Related: #170

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Diffuse report:

OLD: sdk-main.aar
NEW: sdk-pr.aar

 AAR      │ old       │ new       │ diff 
──────────┼───────────┼───────────┼──────
      jar │  51.7 KiB │  51.7 KiB │  0 B 
 manifest │     411 B │     411 B │  0 B 
      res │  78.3 KiB │  78.3 KiB │  0 B 
    other │     954 B │     954 B │  0 B 
──────────┼───────────┼───────────┼──────
    total │ 131.3 KiB │ 131.3 KiB │  0 B 

 JAR     │ old │ new │ diff      
─────────┼─────┼─────┼───────────
 classes │  37 │  37 │ 0 (+0 -0) 
 methods │ 507 │ 507 │ 0 (+0 -0) 
  fields │ 162 │ 162 │ 0 (+0 -0)

[github-actions]

Benchmark report:

Test name	Time ms. (median)	Allocations (median)
com.hcaptcha.sdk.HCaptchaBenchmarkTest.EMULATOR_UNLOCKED_benchmarkInvisibleVerification	+360.88	-6
com.hcaptcha.sdk.HCaptchaBenchmarkTest.EMULATOR_UNLOCKED_benchmarkInvisibleVerificationColdRun	+419.63	+99
com.hcaptcha.sdk.HCaptchaBenchmarkTest.EMULATOR_UNLOCKED_benchmarkInvisibleSetup	-1.46	+94
com.hcaptcha.sdk.HCaptchaDebugInfoTest.EMULATOR_UNLOCKED_benchmarkDebugInfo	-10.71	+556
com.hcaptcha.sdk.HCaptchaDebugInfoTest.EMULATOR_UNLOCKED_benchmarkDebugSys	+26.51	-21