[CALCITE-4299] Test against Go 1.14 and 1.15
diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index f7d6668..5693fde 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -5,7 +5,7 @@
     strategy:
       fail-fast: false
       matrix:
-        go_version: [1.13, 1.14]
+        go_version: [1.14, 1.15]
         database_image:
           - boostport/hbase-phoenix-all-in-one:1.3-4.13
           - boostport/hbase-phoenix-all-in-one:1.4-4.14
diff --git a/docker-compose.yml b/docker-compose.yml
index a123fac..9712713 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -23,7 +23,7 @@
     command: -u jdbc:hsqldb:mem:public
 
   test:
-    image: golang:1.14-alpine
+    image: golang:1.15-alpine
     command: sh -c "apk --no-cache --no-progress add gcc git musl-dev; export AVATICA_FLAVOR=HSQLDB && go test -v ./...; export AVATICA_FLAVOR=PHOENIX && go test -v ./..."
     working_dir: /source
     environment:
@@ -37,7 +37,7 @@
       - hsqldb
 
   dev:
-    image: golang:1.14-alpine
+    image: golang:1.15-alpine
     command: sh -c "apk --no-cache --no-progress add build-base git; go install github.com/unchartedsoftware/witch; cd /source; witch --cmd=\"export AVATICA_FLAVOR=HSQLDB && go test -v ./...; export AVATICA_FLAVOR=PHOENIX && go test -v ./...\" --watch=\"*.mod,**/*.go\""
     environment:
       PHOENIX_HOST: http://phoenix:8765
@@ -88,7 +88,7 @@
       - .:/source
 
   compile-protobuf:
-    image: golang:1.14-alpine
+    image: golang:1.15-alpine
     working_dir: /source
     command: sh -c "apk --no-cache --no-progress add bash; ./docker.sh compile-protobuf"
     environment: