PG-2187 Remove PostgreSQL 13 support

PostgreSQL 13 reached its End of Life, so it's time to remove
compatibility with this version.

Author: artemgavrilov

.github/workflows/postgresql-13-build.yml

@@ -2,7 +2,7 @@
    "name": "pg_stat_monitor",
    "abstract": "PostgreSQL Query Performance Monitoring Tool",
    "description": "pg_stat_monitor is a PostgreSQL Query Performance Monitoring tool, based on PostgreSQL's contrib module pg_stat_statements. PostgreSQL’s pg_stat_statements provides the basic statistics, which is sometimes not enough. The major shortcoming in pg_stat_statements is that it accumulates all the queries and their statistics and does not provide aggregated statistics nor histogram information. In this case, a user would need to calculate the aggregates, which is quite an expensive operation.",
-   "version": "2.3.2",
+   "version": "2.4.0",
    "maintainer": [
       "Artem Gavrilov <artem.gavrilov@percona.com>",
       "Percona PostgreSQL Team <postgresql@percona.com>"
@@ -13,15 +13,15 @@
    "provides": {
       "pg_stat_monitor": {
          "abstract": "PostgreSQL Query Performance Monitoring Tool",
-         "file": "pg_stat_monitor--2.2--2.3.sql",
+         "file": "pg_stat_monitor--2.3--2.4.sql",
          "docfile": "README.md",
-         "version": "2.3.2"
+         "version": "2.4.0"
       }
    },
    "prereqs": {
       "runtime": {
          "requires": {
-            "PostgreSQL": "12.0.0"
+            "PostgreSQL": "14.0.0"
          }
       }
    },