Pin logback-core and logback-classic to 1.2.0

Logback introduced a backwards incompatible change in 1.2.1 which will be fixed in 1.3.0

See this issue for context: logfellow/logstash-logback-encoder#232

In the meantime, we should not upgrade to any of the 1.2.x versions. #182 should be closed.

.github/dependabot.yml

@@ -20,7 +20,14 @@ updates:
     - 2.3.0
   - dependency-name: ch.qos.logback:logback-core
     versions:
+    - 1.2.1
+    - 1.2.2
     - 1.2.3
+  - dependency-name: ch.qos.logback:logback-classic
+    versions:
+      - 1.2.1
+      - 1.2.2
+      - 1.2.3
   - dependency-name: org.apache.pdfbox:pdfbox
     versions:
     - 2.0.22

build.gradle

@@ -107,7 +107,7 @@ dependencies {
     implementation 'ch.qos.logback.contrib:logback-json-classic:0.1.5'
     implementation 'ch.qos.logback.contrib:logback-jackson:0.1.5'
     implementation 'ch.qos.logback:logback-core:1.2.0'
-    implementation 'ch.qos.logback:logback-classic:1.2.3'
+    implementation 'ch.qos.logback:logback-classic:1.2.0'
     implementation 'net.logstash.logback:logstash-logback-encoder:6.6'
 
     implementation(files(genJaxb.classesDir).builtBy(genJaxb))