oauth2-client: migrate apps to use oauth2-client helm chart (#90)

* headscale: use oauth2-client helm chart

* pihole: use oauth2-client helm chart

* matrix: use oauth2-client helm chart

* oauth2: pass issuer address to pihole, headscale and matrix apps

* pihole: fix secret name

* matrix: fix version to v1.98.0

* headscale: make oauth2-client depend on auth release

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Co-authored-by: Giorgi Lekveishvili <lekva@gl-mbp-m1-max.local>
diff --git a/charts/pihole/templates/oauth2-proxy.yaml b/charts/pihole/templates/oauth2-proxy.yaml
index 51f88d4..2d62f7b 100644
--- a/charts/pihole/templates/oauth2-proxy.yaml
+++ b/charts/pihole/templates/oauth2-proxy.yaml
@@ -54,7 +54,7 @@
       volumes:
       - name: config
         configMap:
-          name: {{ .Values.oauth2.configName }}
+          name: {{ .Values.configName }}
       containers:
       - name: pihole-oauth2-proxy
         image: quay.io/oauth2-proxy/oauth2-proxy:v7.2.0