Fix CI builds (#85)

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## References

- TODO

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.github/workflows/build-and-test.yml

@@ -34,4 +34,4 @@ jobs:
       - name: Run the Gradle package task
         uses: gradle/gradle-build-action@v2
         with:
-          arguments: build check
+          arguments: build check

.gitignore

@@ -29,3 +29,4 @@ replay_pid*
 !gradle/wrapper/gradle-wrapper.jar
 build/
 .gradle/
+bin/

build.gradle

@@ -86,10 +86,12 @@ signing {
     required {
         !version.toString().contains("SNAPSHOT") && (gradle.taskGraph.hasTask("uploadArchives") || gradle.taskGraph.hasTask("publish"))
     }
-    def signingKey = providers.environmentVariable("OSSRH_GPG_SECRET_KEY").get()
-    def signingPassphrase = providers.environmentVariable("OSSRH_GPG_SECRET_KEY_PASSWORD").get()
-    useInMemoryPgpKeys(signingKey, signingPassphrase)
-    sign(publishing.publications)
+    def signingKey = providers.environmentVariable("OSSRH_GPG_SECRET_KEY").orElse(null)
+    def signingPassphrase = providers.environmentVariable("OSSRH_GPG_SECRET_KEY_PASSWORD").orElse(null)
+    if (signingKey != null && signingPassphrase != null) {
+        useInMemoryPgpKeys(signingKey, signingPassphrase)
+        sign(publishing.publications)
+    }
 }
 
 publishing {