Replace broken mergo version

Replace mergo version used by controller-runtime which is broken [0],
until we can move to controller-runtime 0.7.0 which no longer uses this version.

Fixes #152

[0]: darccio/mergo#139

Signed-off-by: Sean Eagan <seaneagan1@gmail.com>

go.mod

@@ -3,6 +3,8 @@ module github.com/fluxcd/helm-controller
 go 1.15
 
 replace github.com/fluxcd/helm-controller/api => ./api
+// TODO: Remove once we move to a controller-runtime version which doesn't use this version.
+replace github.com/imdario/mergo v0.3.9 => github.com/imdario/mergo v0.3.8
 
 require (
 	github.com/fluxcd/helm-controller/api v0.4.1
@@ -23,3 +25,4 @@ require (
 	sigs.k8s.io/controller-runtime v0.6.3
 	sigs.k8s.io/yaml v1.2.0
 )
+

go.sum

@@ -423,9 +423,8 @@ github.com/huandu/xstrings v1.3.1/go.mod h1:y5/lhBue+AyNmUVz9RLU9xbLR0o4KIIExikq
 github.com/hudl/fargo v1.3.0/go.mod h1:y3CKSmjA+wD2gak7sUSXTAoopbhU08POFhmITJgmKTg=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
 github.com/imdario/mergo v0.3.5/go.mod h1:2EnlNZ0deacrJVfApfmtdGgDfMuh/nq6Ok1EcJh5FfA=
+github.com/imdario/mergo v0.3.8 h1:CGgOkSJeqMRmt0D9XLWExdT4m4F1vd3FV3VPt+0VxkQ=
 github.com/imdario/mergo v0.3.8/go.mod h1:2EnlNZ0deacrJVfApfmtdGgDfMuh/nq6Ok1EcJh5FfA=
-github.com/imdario/mergo v0.3.9 h1:UauaLniWCFHWd+Jp9oCEkTBj8VO/9DKg3PV3VCNMDIg=
-github.com/imdario/mergo v0.3.9/go.mod h1:2EnlNZ0deacrJVfApfmtdGgDfMuh/nq6Ok1EcJh5FfA=
 github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/influxdata/influxdb1-client v0.0.0-20191209144304-8bf82d3c094d/go.mod h1:qj24IKcXYK6Iy9ceXlo3Tc+vtHo9lIhSX5JddghvEPo=