*/*: update for slotted Rust

guru version of this commit:
https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=01ba4dc61965ef7658a24728841c04c9a1ce4871

Closes: https://bugs.gentoo.org/943170
Closes: https://bugs.gentoo.org/943223
Closes: #260
Signed-off-by: Takuya Wakazono <pastalian46@gmail.com>

net-im/conduit/conduit-0.8.0-r1.ebuild

@@ -390,6 +390,8 @@ declare -A GIT_CRATES=(
 	[ruma]='https://github.com/ruma/ruma;ef40b184b7410a93e933b4ad719a72aea1bdd20e;ruma-%commit%/crates/ruma'
 )
 
+RUST_MIN_VER="1.75.0"
+
 inherit cargo systemd toolchain-funcs
 
 MY_P="${PN}-v${PV}"
@@ -441,7 +443,6 @@ RDEPEND="${DEPEND}
 	app-misc/ca-certificates
 "
 BDEPEND="
-	>=virtual/rust-1.75.0
 	rocksdb? (
 		sys-devel/clang
 		virtual/pkgconfig

net-im/conduit/conduit-0.9.0-r1.ebuild

@@ -390,6 +390,8 @@ declare -A GIT_CRATES=(
 	[ruma]='https://github.com/ruma/ruma;c06af4385e0e30c48a8e9ca3d488da32102d0db9;ruma-%commit%/crates/ruma'
 )
 
+RUST_MIN_VER="1.75.0"
+
 inherit cargo systemd toolchain-funcs
 
 MY_P="${PN}-v${PV}"
@@ -441,7 +443,6 @@ RDEPEND="${DEPEND}
 	app-misc/ca-certificates
 "
 BDEPEND="
-	>=virtual/rust-1.75.0
 	rocksdb? (
 		sys-devel/clang
 		virtual/pkgconfig

net-im/conduit/conduit-9999.ebuild

@@ -5,6 +5,8 @@
 
 EAPI=8
 
+RUST_MIN_VER="1.75.0"
+
 inherit cargo git-r3 systemd toolchain-funcs
 
 DESCRIPTION="Matrix homeserver written in Rust"
@@ -52,7 +54,6 @@ RDEPEND="${DEPEND}
 	app-misc/ca-certificates
 "
 BDEPEND="
-	>=virtual/rust-1.75.0
 	rocksdb? (
 		sys-devel/clang
 		virtual/pkgconfig

net-im/flare/flare-0.12.0-r1.ebuild

@@ -3,7 +3,7 @@
 
 EAPI=8
 
-inherit gnome2-utils meson xdg
+inherit gnome2-utils meson rust xdg
 
 PKG_ID=112823190
 DESCRIPTION="Chat with your friends on Signal"
@@ -50,7 +50,6 @@ BDEPEND="
 	dev-libs/glib:2
 	dev-util/blueprint-compiler
 	sys-devel/gettext
-	virtual/rust
 "
 
 QA_FLAGS_IGNORED="usr/bin/${PN}"