server+README: bump minimum required lnd version to v0.15.4-beta

Since any version prior to v0.15.4-beta will not sync to the mainnet
chain, we can safely bump the minimum required version to that since no
older version will be running (properly) anywhere.

README.md

@@ -47,7 +47,7 @@ Download the latest binaries from the
 ## LND
 
 Note that Pool requires `lnd` to be built with **all of its subservers** and
-requires running at least `v0.14.3`. Download the latest [official release
+requires running at least `v0.15.4`. Download the latest [official release
 binary](https://github.com/lightningnetwork/lnd/releases/latest) or build `lnd`
 from source by following the [installation
 instructions](https://github.com/lightningnetwork/lnd/blob/master/docs/INSTALL.md).
@@ -81,7 +81,7 @@ to help in any way we can. In the meantime please see our
 [FAQs](https://pool.lightning.engineering/faq).
 
 ## Build from source
-If you’d prefer to compile from source code, you’ll need at least `go 1.17` and
+If you’d prefer to compile from source code, you’ll need at least `go 1.18` and
 `make`.
 
 Run the following commands to download the code, compile and install Pool:
@@ -95,5 +95,5 @@ $ make install
 This will install the binaries into your `$GOPATH/bin` directory.
 
 ## Compatibility
-Lightning Pool requires `lnd` version `0.14.3-beta` or higher (`v0.15.0-beta` or
+Lightning Pool requires `lnd` version `0.15.4-beta` or higher (`v0.16.0-beta` or
 later is recommended).

server.go

@@ -45,7 +45,7 @@ var (
 	minimalCompatibleVersion = &verrpc.Version{
 		AppMajor: 0,
 		AppMinor: 15,
-		AppPatch: 1,
+		AppPatch: 4,
 
 		// We don't actually require the invoicesrpc calls. But if we
 		// try to use lndclient on an lnd that doesn't have it enabled,