Remove support for v9.5.

Standard Support for both EDB Postgres Advanced Server 9.5 and
PostgreSQL 9.5 ended in February 2021.  Adjust Makefile so that
we restrict compilation of mysql_fdw code against v9.5.  Update
the README accordingly.

Suraj Kharage

Makefile

@@ -40,8 +40,8 @@ include $(PGXS)
 ifndef MAJORVERSION
 MAJORVERSION := $(basename $(VERSION))
 endif
-ifeq (,$(findstring $(MAJORVERSION), 9.5 9.6 10 11 12 13))
-$(error PostgreSQL 9.5, 9.6, 10, 11, 12, or 13 is required to compile this extension)
+ifeq (,$(findstring $(MAJORVERSION), 9.6 10 11 12 13))
+$(error PostgreSQL 9.6, 10, 11, 12, or 13 is required to compile this extension)
 endif
 
 else

README.md

@@ -5,7 +5,7 @@ This PostgreSQL extension implements a Foreign Data Wrapper (FDW) for
 [MySQL][1].
 
 Please note that this version of mysql_fdw works with PostgreSQL and EDB
-Postgres Advanced Server 9.5, 9.6, 10, 11, 12, and 13.
+Postgres Advanced Server 9.6, 10, 11, 12, and 13.
 
 Installation
 ------------