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

---------

Co-authored-by: Giorgi Lekveishvili <lekva@gl-mbp-m1-max.local>
diff --git a/charts/pihole/values.yaml b/charts/pihole/values.yaml
index 070be1e..542fcd3 100644
--- a/charts/pihole/values.yaml
+++ b/charts/pihole/values.yaml
@@ -1,10 +1,10 @@
 pihole: {}
 oauth2:
   cookieSecret: "1234123443214321"
-  secretName: oauth2-secret
-  configName: oauth2-proxy
+  secretName: oauth2-client
+  issuer: https://oidc-issuer.example.com
+configName: oauth2-proxy
 domain: pihole.p.example.com
-hydraPublic: https://hydra.example.com
 profileUrl: https://profile.example.com
 ingressClassName: private