Enforce linux-headers version (>=4.9)

* This helps ensure that if a RPi attempts to download linux
  headers it won't use that horrible 3.6-trunk-rpi that kills
  dkms.

Change-Id: I8fd5b1b2b71a1ed2dfb85fe6f1f9f72628769944
diff --git a/coral-enviro-drivers/debian/changelog b/coral-enviro-drivers/debian/changelog
index 7a57d4c..d6ef17c 100644
--- a/coral-enviro-drivers/debian/changelog
+++ b/coral-enviro-drivers/debian/changelog
@@ -1,3 +1,9 @@
+coral-enviro-drivers-dkms (1.4) stable; urgency=medium
+
+  * Enforce linux-headers version (>=4.9)
+
+ -- Coral <coral-support@google.com>  Tue, 21 May 2019 15:17:40 +0200
+
 coral-enviro-drivers-dkms (1.3) stable; urgency=medium
 
   * Add tla202x to i2c_device_id table of ti-ads1015
diff --git a/coral-enviro-drivers/debian/control b/coral-enviro-drivers/debian/control
index cfa32e2..d0f7019 100644
--- a/coral-enviro-drivers/debian/control
+++ b/coral-enviro-drivers/debian/control
@@ -7,6 +7,6 @@
 
 Package: coral-enviro-drivers-dkms
 Architecture: all
-Depends: dkms (>= 1.95), raspberrypi-kernel-headers | linux-headers, ${misc:Depends}
+Depends: dkms (>= 1.95), raspberrypi-kernel-headers | linux-headers (>= 4.9), ${misc:Depends}
 Description: Coral Environmental Sensor Board DKMS drivers.
  Required drivers for the Environmental Sensor Board.