chore: regenerate README versions (#311)

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Author: yoshi-automation

README.md

@@ -17,7 +17,7 @@ If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>libraries-bom</artifactId>
-      <version>7.0.1</version>
+      <version>8.0.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>
@@ -38,7 +38,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-spanner</artifactId>
-  <version>1.55.1</version>
+  <version>1.56.0</version>
 </dependency>
 
 ```

google-cloud-spanner/src/test/java/com/google/cloud/spanner/admin/database/v1/DatabaseAdminClientTest.java

@@ -115,7 +115,7 @@ public void setUp() throws IOException {
   }
 
   @After
-  public void tearDown() {
+  public void tearDown() throws Exception {
     client.close();
   }
 

google-cloud-spanner/src/test/java/com/google/cloud/spanner/admin/instance/v1/InstanceAdminClientTest.java

@@ -103,7 +103,7 @@ public void setUp() throws IOException {
   }
 
   @After
-  public void tearDown() {
+  public void tearDown() throws Exception {
     client.close();
   }
 

google-cloud-spanner/src/test/java/com/google/cloud/spanner/v1/SpannerClientTest.java

@@ -108,7 +108,7 @@ public void setUp() throws IOException {
   }
 
   @After
-  public void tearDown() {
+  public void tearDown() throws Exception {
     client.close();
   }
 

synth.metadata

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-spanner.git",
-        "sha": "39826d2d789ab0f9d9046161627ed34969bdef78"
+        "sha": "3d479e4ac478b8a46bbb77c74ca0d08876d74db6"
       }
     },
     {