Remove unused dependencies.

pom.xml

@@ -30,9 +30,6 @@
     <io7m.api.previousVersion>1.0.0</io7m.api.previousVersion>
     <io7m.java.targetJavaVersion>17</io7m.java.targetJavaVersion>
 
-    <!-- io7m dependencies. -->
-    <com.io7m.xstructural.version>1.8.0</com.io7m.xstructural.version>
-
     <!-- Third-party dependencies. -->
     <junit.version>5.10.2</junit.version>
     <jqwik.version>1.8.4</jqwik.version>
@@ -92,17 +89,7 @@
 
   <dependencyManagement>
     <dependencies>
-      <dependency>
-        <groupId>org.slf4j</groupId>
-        <artifactId>slf4j-api</artifactId>
-        <version>2.0.13</version>
-      </dependency>
-      <dependency>
-        <groupId>ch.qos.logback</groupId>
-        <artifactId>logback-classic</artifactId>
-        <version>1.5.6</version>
-      </dependency>
-
+      <!-- Build and metadata. -->
       <dependency>
         <groupId>org.osgi</groupId>
         <artifactId>org.osgi.annotation.bundle</artifactId>
@@ -118,16 +105,6 @@
         <artifactId>com.io7m.primogenitor.support</artifactId>
         <version>8.2.0</version>
       </dependency>
-      <dependency>
-        <groupId>com.io7m.lanark</groupId>
-        <artifactId>com.io7m.lanark.core</artifactId>
-        <version>1.2.0</version>
-      </dependency>
-      <dependency>
-        <groupId>com.io7m.jdeferthrow</groupId>
-        <artifactId>com.io7m.jdeferthrow.core</artifactId>
-        <version>1.3.0</version>
-      </dependency>
 
       <!-- Test suite. -->
       <dependency>