Update buf.gen.yaml versions for protobuf (#299)

This updates all buf.gen.yaml files to the latest version of protobuf
(v31.1)

Author: smaye81

buf.gen.yaml

@@ -1,5 +1,5 @@
 version: v2
 clean: true
 plugins:
-  - remote: buf.build/protocolbuffers/java:v31.0
+  - remote: buf.build/protocolbuffers/java:v31.1
     out: build/generated/sources/bufgen

conformance/buf.gen.yaml

@@ -6,5 +6,5 @@ managed:
     - file_option: java_package_prefix
       value: build
 plugins:
-  - remote: buf.build/protocolbuffers/java:v31.0
+  - remote: buf.build/protocolbuffers/java:v31.1
     out: build/generated/sources/bufgen

src/test/resources/proto/buf.gen.cel.testtypes.yaml

@@ -5,5 +5,5 @@ managed:
     - file_option: java_package
       value: cel.expr.conformance.proto3
 plugins:
-  - remote: buf.build/protocolbuffers/java:v31.0
+  - remote: buf.build/protocolbuffers/java:v31.1
     out: build/generated/test-sources/bufgen

src/test/resources/proto/buf.gen.cel.yaml

@@ -2,5 +2,5 @@ version: v2
 managed:
   enabled: true
 plugins:
-  - remote: buf.build/protocolbuffers/java:v31.0
+  - remote: buf.build/protocolbuffers/java:v31.1
     out: build/generated/test-sources/bufgen

src/test/resources/proto/buf.gen.imports.yaml

@@ -5,7 +5,7 @@ managed:
     - file_option: java_package_prefix
       value: com.example.imports
 plugins:
-  - remote: buf.build/protocolbuffers/java:v31.0
+  - remote: buf.build/protocolbuffers/java:v31.1
     out: build/generated/test-sources/bufgen
 inputs:
   - directory: src/test/resources/proto

src/test/resources/proto/buf.gen.noimports.yaml

@@ -8,7 +8,7 @@ managed:
     - file_option: java_package_prefix
       value: com.example.noimports
 plugins:
-  - remote: buf.build/protocolbuffers/java:v31.0
+  - remote: buf.build/protocolbuffers/java:v31.1
     out: build/generated/test-sources/bufgen
 inputs:
   - directory: src/main/resources